The scores are assigned to people entering and leaving the United States after computers assess their travel records, including where they are from, how they paid for tickets, their motor vehicle records, past one-way travel, seating preference and what kind of meal they ordered.

The program's existence was quietly disclosed earlier in November when the government put an announcement detailing the Automated Targeting System, or ATS, for the first time in the Federal Register, a fine-print compendium of federal rules. Privacy and civil liberties lawyers, congressional aides and even law enforcement officers said they thought this system had been applied only to cargo.

The Homeland Security Department notice called its program "one of the most advanced targeting systems in the world." The department said the nation's ability to spot criminals and other security threats "would be critically impaired without access to this data."

Still, privacy advocates view ATS with alarm. "It's probably the most invasive system the government has yet deployed in terms of the number of people affected," David Sobel, a lawyer at the Electronic Frontier Foundation, a civil liberties group devoted to electronic data issues, said in an interview.
A similar Homeland Security data-mining project, for domestic air travellers - now known as Secure Flight - caused a furor two years ago in Congress. Legislators barred its implementation until it can pass 10 tests for accuracy and privacy protection.

In comments to the Homeland Security Department about ATS, Sobel said, "Some individuals will be denied the right to travel and many the right to travel free of unwarranted interference as a result of the maintenance of such material."

Sobel said in the interview the government notice also raises the possibility that faulty risk assessments could cost innocent people jobs in shipping or travel, government contracts, licenses or other benefits.

The government notice says ATS data may be shared with state, local and foreign governments for use in hiring decisions and in granting licenses, security clearances, contracts or other benefits. In some cases, the data may be shared with courts, Congress and even private contractors.

"Everybody else can see it, but you can't," Stephen Yale-Loeher, an immigration lawyer who teaches at Cornell Law school, said in an interview.

But Jayson P. Ahern, an assistant commissioner of Homeland Security's Customs and Border Protection agency, said the ATS ratings simply allow agents at the border to pick out people not previously identified by law enforcement as potential terrorists or criminals and send them for additional searches and interviews. "It does not replace the judgements of officers," Ahern said in an interview Thursday.

This targeting system goes beyond traditional border watch lists, Ahern said. Border agents compare arrival names with watch lists separately from the ATS analysis.

In a privacy impact assessment posted on its website this week, Homeland Security said ATS is aimed at discovering high-risk individuals who "may not have been previously associated with a law enforcement action or otherwise be noted as a person of concern to law enforcement."

Ahern said ATS does this by applying rules derived from the government's knowledge of terrorists and criminals to the passenger's travel patterns and records.

He said any traveller who objected to additional searches or interviews could ask to speak to a supervisor to complain. Homeland Security's privacy impact statement said that if asked, border agents would hand complaining passengers a one-page document that describes some, but not all, of the records that agents check and refers complaints to Custom and Border Protection's Customer Satisfaction Unit.

Homeland Security's statement said travellers can use this office to obtain corrections to the underlying data sources that the risk assessment is based on. "There is no procedure to correct the risk assessment and associated rules stored in ATS as the assessment ... will change when the data from the source system(s) is amended."

"I don't buy that at all," said Jim Malmberg, executive director of American Consumer Credit Education Support Services, a private credit education group. Malmberg noted how hard it has been for citizens, including members of Congress and even infants, to stop being misidentified as terrorists because their names match those on anti-terrorism watch lists.

The department says that 87 million people a year enter the country by air and 309 million enter by land or sea. The government gets advance passenger and crew lists for all flights and ships entering and leaving and all those names are entered into the system for an ATS analysis, Ahern said. He also said the names of vehicle drivers and passengers are entered when they cross the border and Amtrak is voluntarily supplying passenger data for trains to and from Canada.

Ahern said that border agents concentrate on arrivals more than on departures because their resources are limited.

"If this catches one potential terrorist, this is a success," Ahern said.

'It was love at first sight for Luis and me, and that's how it stayed, after two years dating at school and eight years of marriage,' says Janet. 'We always spoke a couple of times during the day and he always kept his phone on. So I called my dad, who owns the truckyard where he worked and he told me, "he hasn't been here". I called my in-laws and they hadn't seen him either, and they were already worried because his car was outside their house with the windows open and the keys in the ignition. He would never normally leave it like that.'

Luis Padilla, 29, father of three, had been kidnapped, driven across the Mexican border from El Paso, Texas, to a house in Ciudad Juarez, the lawless city ruled by drug lords that lies across the Rio Grande. As his wife tried frantically to locate him, he was being stripped, tortured and buried in a mass grave in the garden - what the people of Juarez call a narco-fossa, a narco-smugglers' tomb.

Just another casualty of Mexico's drug wars? Perhaps. But Padilla had no connection with the drugs trade; he seems to have been the victim of a case of mistaken identity. Now, as a result of documents disclosed in three separate court cases, it is becoming clear that his murder, along with at least 11 further brutal killings, at the Juarez 'House of Death', is part of a gruesome scandal, a web of connivance and cover-up stretching from the wild Texas borderland to top Washington officials close to President Bush.

These documents, which form a dossier several inches thick, are the main source for the facts in this article. They suggest that while the eyes of the world have been largely averted, America's 'war on drugs' has moved to a new phase of cynicism and amorality, in which the loss of human life has lost all importance - especially if the victims are Hispanic. The US agencies and officials in this saga - all of which refused to comment, citing pending lawsuits - appear to have thought it more important to get information about drugs trafficking than to stop its perpetrators killing people.

The US media have virtually ignored this story. The Observer is the first newspaper to have spoken to Janet Padilla, and this is the first narrative account to appear in print. The story turns on one extraordinary fact: playing a central role in the House of Death was a US government informant, Guillermo Ramirez Peyro, known as Lalo, who was paid more than $220,000 (£110,000) by US law enforcement bodies to work as a spy inside the Juarez cartel. In August 2003 Lalo bought the quicklime used to dissolve the flesh of the first victim, Mexican lawyer Fernando Reyes, and then helped to kill him; he recorded the murder secretly with a bug supplied by his handlers - agents from the Immigration and Customs Executive (Ice), part of the Department of Homeland Security. That first killing threw the Ice staff in El Paso into a panic. Their informant had helped to commit first-degree murder, and they feared they would have to end his contract and abort the operations for which he was being used. But the Department of Justice told them to proceed.

Lalo's cartel bosses told him whenever they were planning another killing, using a grisly codeword - carne asada, 'barbecue'. In the six months after Reyes's death, they used it on many occasions. Each time, says Lalo, he informed his handlers in Ice. They did not intervene.

El Paso, population 700,000, lies in Texas's far west. It is a V-shaped city almost bisected by the Franklin mountains, lashed by desert winds. Houston and Dallas are more than 600 miles away. Much closer, across a guarded fence and the river, here little wider than a stream, is Juarez. On the western side of the Mexican city are the barrios - dirt streets of ramshackle huts without sanitation, built from discarded wood and tyres, whose inhabitants live in sight of the gleaming offices of downtown El Paso.

Eastern Juarez is very different. There, in the campestre, the country club district, lie gated developments patrolled by security guards, armoured palaces of marble, with columns, fountains and huge golden domes. Most of the money comes from drugs. Los narcos control not only Juarez but the wider state of Chihuahua, ruling through corruption and fear. One organisation is paramount - the Juarez cartel led by Vicente Carrillo Fuentes. The US State Department claims he is responsible for shipping cocaine and marijuana worth billions of dollars a year and protects his business by killing. America is offering a $5m reward for his arrest.

His cartel has penetrated Mexican law enforcement at all levels. Like many of its operatives, Lalo began as a policeman - in his case in the Mexican highway police. Having resigned from the force in 1995, he began transporting cocaine by the ton for a gang based in Guadalajara. Professing disgust at his criminal associates, he started working for the US government in February 2000, supplying information not only to Ice (then known as US Customs) but also the Drug Enforcement Administration (DEA), the Bureau of Alcohol, Firearms and Tobacco, and the FBI. A few months later, with his handlers' encouragement, he was recruited into the Juarez cartel by Il Ingeniero, the Engineer, one of Fuentes's key lieutenants and a man notorious for acts of savage violence. His real name was Heriberto Santillan-Tabares.

'The money I got from the Americans I invested in business,' says Lalo, 36. 'I had a used-car lot, a furniture store and a cellphone accessory place.' He settled with his wife and three children on the US side of the border. 'I spoke to my handlers three or four times a day. But when I went across the bridge to Juarez, I had no back-up. I was on my own.'

Lalo claims to have facilitated numerous drug seizures and arrests. But on 28 June, 2003, his loyalty came under suspicion when he was arrested by the DEA in New Mexico, driving a truck he had brought across the border containing 102lb of marijuana. He had not told his handlers about this shipment and, in accordance with its normal procedures, the DEA 'deactivated' him as a source.

Ice took a different view. Agents in its El Paso office were trying to use Lalo to build a case against Santillan, and to nail a separate cigarette-smuggling investigation. At a meeting with federal prosecutors the week after Lalo's arrest, Ice tried to persuade assistant US attorney Juanita Fielden that, if Lalo were closely monitored, he would continue to be effective. Fielden agreed. She says in an affidavit that she called the New Mexico prosecutor and got him to drop the charges. Lalo was released.

A month later, on 5 August, Santillan asked Lalo to meet him at a cartel safe house at 3633 Calle Parsonieros, in an affluent neighbourhood of Juarez. The Mexican lawyer Reyes would be there too, Santillan said, and with the help of some members of the Juarez judicial police - the local detective force - they were going to kill him.

When Lalo arrived, two cops were already there. He went out to buy the quicklime and duct tape, and when he returned Santillan turned up with Reyes. The policemen jumped on the lawyer, beating him and trying to put duct tape over his mouth. Lalo, wearing his hidden wire supplied by Ice, recorded Reyes's desperate pleas for mercy. 'They [the police] asked me to help them get him to the floor,' reads a statement he made later. 'They tried to choke him with an extension cord, but this broke and I gave them a plastic bag and they put it on his head and suffocated him.' Even then, they were not sure Reyes was dead. One of the officers took a shovel 'and hit him many times on the head'.

When Lalo returned to El Paso on the day of Reyes's murder and told his Ice employers what had happened they were understandably worried. They knew that, if they were to continue using Lalo as an informant, they would need high-level authorisation. That afternoon and evening he was debriefed at length by his main handler, Special Agent Raul Bencomo, and his supervisor. Then he was allowed to go back to Juarez - Santillan had given him $2,000 to pay two cartel members to dig Reyes's grave, cover his body with quicklime and bury it.

Meanwhile the El Paso Ice office reported the matter to headquarters in Washington. The information went up the chain of command, eventually reaching America's Deputy Assistant Attorney General, John G. Malcolm. It passed through the office of Johnny Sutton, the US Attorney for Western Texas - a close associate of George W. Bush. When Bush was Texas governor, Sutton spent five years as his director of criminal justice policy. After Bush became President, Sutton became legal policy co-ordinator in the White House transition team, working with another Bush Texas colleague, Alberto Gonzalez, the present US Attorney General.

Earlier this year Sutton was appointed chairman of the Attorney General's advisory committee which, says the official website, 'plays a significant role in determining policies and programmes of the department and in carrying out the national goals set by the President and the Attorney General'. Sutton's position as US Attorney for Western Texas is further evidence of his long friendship with the President - falling into his jurisdiction is Midland, the town where Bush grew up, and Crawford, the site of Bush's beloved ranch.

'Sutton could and should have shut down the case, there and then,' says Bill Weaver, a law professor at the University of Texas at El Paso who has made a detailed study of the affair. 'He could have told Ice and the lawyers "go with what you have, and let's try to bring Santillan to justice". That neither he nor anyone else decided to take that action invites an obvious inference: that because the only people likely to get killed were Mexicans, they thought it didn't much matter.'

In the days after Reyes's death, officials in Texas and Washington held a series of meetings. Finally word came back from headquarters - despite the risk that Lalo might become involved with further murders, Ice could continue to use and pay him as an informant. And although Santillan had already been caught on tape directing a merciless killing and might well kill again, no attempt would be made to arrest him.

Lalo's statement, made in Dallas in February 2004, is a record of cruelty and violence, the words of a man who thought himself untouchable because of his relationship with Ice. In the months after Washington decided not to move on Santillan, the garden of the house at 3633 Calle Parsonieros began to fill with bodies. One day in September 2003, 'Santillan called to ask me to bury a guy who had apparently died of a heart attack at the moment he was kidnapped', Lalo's statement says. 'Another execution I remember was on 23 November... Santillan ordered me to have these drug mules meet him in the little Parsonieros house ... Loya [a corrupt police commander] put tape around their heads, but they could still breathe and one of them began to moan loudly, so Loya shot him in the head... but he didn't die immediately.' They were killed because they were careless in their smuggling work.

Then, and on other occasions, Santillan told Lalo in advance he was going to hold a carne asada. The deposition gives details of 13 murders, all but one of whose victims were later found buried at Number 3633. Each time Lalo crossed into Mexico his Ice handlers sought and obtained formal clearance from headquarters to allow their source to travel to a foreign country while working for a US agency. Throughout the period, Lalo says, he continued to talk to his handler Bencomo up to four times a day - usually in person, at the Ice El Paso office. He says his meetings with Santillan were all covertly recorded, while documents show that Ice had arranged for Lalo's phone to be bugged.

Curtis Compton, Bencomo's Ice supervisor, insisted in an affidavit that it did not know of any murders before they occurred: 'We only learned about the murders through interviews of Lalo after the fact. I acted in good faith that all my actions were legal and proper.'

Lalo's last country clearance was issued on 13 January, 2004. Once again Santillan had called him, asking him to come to Juarez to unlock the Parsonieros house for a carne asada. Next morning Luis Padilla disappeared.

Although the Padillas had attended Socorro high school in El Paso and lived in the US from childhood, both remained Mexican citizens, resident aliens with green-card work permits. Their children, Luis jnr, Jacqueline and Jasmine, were born in the US. Luis snr was two years ahead of Janet at school and they did not speak to each other until they attended a mutual friend's quinceria, a 15th birthday party.

Janet smiles at the memory: 'I liked everything about Luis straight away. He was silly, funny, a popular guy; he played a lot of sports. He was very religious and I started going to the same church, where he was president of the youth section.' For their first date he took her to a Mexican restaurant, and then a children's park: 'We just sat there on the swings, talking as if we'd known each other for years.' In 1996, when Janet was 16, they got married. They spent their wedding night in Juarez.

By 4pm on 14 January, Janet was on the point of phoning El Paso police when she received a call from a friend in Juarez. 'She told me, "I've just seen Luis over here. He was with some cops - they were putting him in a truck". I couldn't figure it out. He shouldn't have been in Mexico at all. At 8 o'clock I couldn't stand it any longer and I went over there myself. I went to all the different police stations. Nobody had him. Nobody knew where he was.'

Since they married Janet and Luis had only ever spent a night apart - when Luis junior was born; they had been living in Dallas, but she wanted to give birth in El Paso, in order to be near her family. In the fortnight after his disappearance, Janet and the children stayed with relatives. 'I couldn't go home. I couldn't be on my own. When he was lost, not knowing what had happened drove me crazy. When at last I heard something, at first I felt relief. A lot of people disappear in Juarez and you never know what happened to them.'

On 26 January, Janet got a call. Juarez police told her they had found some bodies. She was to meet them at the city mortuary. First, she was shown some photographs, but none was of Luis, 'I had to do it in person. I went in there and they had four bodies at that time. There were still ropes around their heads and their eyes were sticking out because they had been suffocated. It was horrible, horrible. One of them had a tattoo, one had silver teeth, another was too fat.'

Janet still did not believe this could have anything to do with Luis. 'He never took drugs and he never drank, beyond the odd beer. He never got into fights. He was still really into the church and he'd just been asked to coach middle-school sports. How could he be narco-fossa?' The police phoned again. This time they asked her to meet them at 3633 Calle Parsonieros. The place looked familiar. 'The hotel where we spent our honeymoon night backed on to the garden.

'I saw his shoes and his jacket. I went into the garden and they were probing the ground with a pole. That's when they found his body.' The police exhumed him, 'but it was hard to ID him because he was so decomposed. I looked at his hands and touched them. The flesh fell off.'

Two other men had been murdered on 14 January, both of them from Juarez. The next day Santillan told Lalo he had been asked to kill them as a favour for some associates of Vicente Carrillo Fuentes - Santillan had nothing against them personally. In such circumstances, murderers can make mistakes.

While Santillan and Lalo went on killing, Bencomo, his Ice colleagues and Assistant US Attorney Fielden were assembling their case. In December 2003 Fielden drew up a sealed indictment against Santillan. But although there was already some evidence of his involvement in killings, the indictment was only for trafficking, not murder. Before they could lure him to America and arrest him, they needed permission from the DoJ. They got it on 15 January, a day after Luis Padilla died.

But this did not bring the House of Death killings to an end. Under torture, one of Santillan's victims had revealed the address of Homer Glen McBrayer - a DEA special agent resident in Juarez who operated under diplomatic cover. At 6pm on 14 January, two men rang his doorbell continuously for 10 minutes. Afraid, his wife phoned him at work. McBrayer rushed home and ushered his wife and daughters into their car. As soon as they left the estate where they lived, they were stopped by a Mexican police car. Two civilian vehicles hemmed McBrayer's car in. Their occupants got out and waited while McBrayer talked to the cops. They were Santillan's men.

Having showed his diplomatic passport, McBrayer phoned a DEA colleague, who arrived within minutes. Unwilling, perhaps, to abduct two US agents, a woman and two children on a busy street, the cartel men backed off. As the standoff unfolded, Santillan twice called Lalo. He asked him to find out what he could about an American called Homer Glen - the corrupt police had not given McBrayer's surname. Santillan, claimed Lalo, said he thought he worked for the tres letras - code for the DEA - and intended to blow up his house.

The McBrayers were lucky to be alive, and the DEA, kept in the dark about the continued use of Lalo after the first murder six months earlier, reacted with fury. Even as Ice debriefed Lalo, it refused the DEA access to him and to recordings of the events of 14 January. Every principle governing informant handling and inter-agency co-operation appeared to have been flouted, and the Mexican government was not told of the carnage taking place on - and under - its soil.

Ice got Lalo to arrange a meeting with Santillan in El Paso and on 15 January Il Ingeniero was arrested. Two days later, Ice finally told the Mexicans that the garden at 3633 Calle Parsonieros was a mass grave. After bureaucratic delays, digging began on 23 January. On 18 February, Johnny Sutton filed a new indictment against Santillan, charging him with trafficking and five murders - including those of Reyes and Padilla.

The House Of Death suddenly seemed set to become a major national scandal. Bill Conroy, a reporter who works for an investigative website, Narconews.com, was about to publish an article about it. On 24 February, Sandy Gonzalez, the Special Agent in Charge of the DEA office in El Paso, one of the most senior and highly decorated Hispanic law enforcement officers in America, wrote to his Ice counterpart, John Gaudioso.

'I am writing to express to you my frustration and outrage at the mishandling of investigation that has resulted in unnecessary loss of human life,' he began, 'and endangered the lives of special agents of the DEA and their immediate families. There is no excuse for the events that culminated during the evening of 14 January... and I have no choice but to hold you responsible.' Ice, Gonzalez wrote, had gone to 'extreme lengths' to protect an informant who was, in reality, a 'homicidal maniac... this situation is so bizarre that, even as I'm writing to you, it is difficult for me to believe it'.

But Ice and its allies in the DoJ were covering up their actions, helped by the US media - aside from the Dallas Morning News, not one major newspaper or TV network has covered the story. The first signs came in the response to Gonzalez's letter to Gaudioso - not from Ice, but from Johnny Sutton.

He reacted not to the discovery of corpses at Calle Parsonieros, but with concern Gonzalez might talk to the media. He communicated his fears to a senior official in Washington - Catherine O'Neil, director of the DoJ's Organised Crime Drug Enforcement Task Force. Describing Gonzalez's letter as 'inflammatory,' she passed on Sutton's fears to the then Attorney General, John Ashcroft, and to Karen Tandy, the head of the DEA, another Texan lawyer.

Tandy was horrified by Gonzalez's letter. 'I apologised to Johnny Sutton last night and he and I agreed on a "no comment" to the press,' she replied on 5 March. Gonzalez would have no further involvement with the House of Death case and was ordered to report to Washington for 'performance discussions to further address this officially'.

Gonzalez was told that Sutton was 'extremely upset'. Gonzalez, who had enjoyed glittering appraisals throughout his 30-year career, was told he would be downgraded. On 4 May, DEA managers in Washington sent him a letter. It said that, if he quietly retired before 30 June, he would be given a 'positive' reference for future employers. If he refused, a reference would dwell on his 'lapse'. Gonzalez resigned, and launched a lawsuit - part of which is due to come to court tomorrow.

'I've been written off,' he says. 'They dismiss my complaints, saying I'm just a disgruntled employee. But once they knew about the carne asadas, they were legally and morally obligated to do something. They already had a solid case against Santillan for drugs and murder. What the fuck else did they need? As for the DEA, they held my feet to the fire and joined the cover-up.' He had been neutralised, but there remained the danger that details of Ice's relationship with Lalo would surface at Santillan's trial.

Janet Padilla had also been dealt with. Ice has no legal responsibility for investigating murder, but after her husband's funeral Lalo's former handler, Bencomo, came calling. 'He told me that he was going to help me find my husband's killers and bring them to justice,' Janet says. 'He said to tell him anything I knew, because he would be in charge of the case. I saw him three or four times, and later I also met Juanita Fielden.' It did not occur to Janet that she ought to contact the police or other agencies.

For Janet, Santillan's indictment for murder was a moment of hope: 'I thought I was going to get justice for Luis.' But on 19 April Sutton announced a deal with Santillan - in return for his pleading guilty to trafficking and acceptance of a 25-year sentence the murder charges were dropped. 'All of the murders were committed in Juarez, by Mexican citizens, and all of the victims were citizens of Mexico,' Sutton said.

No one had any further use for Lalo. In August 2004 someone tried to shoot him at an El Paso restaurant - instead killing an innocent bystander. After that, he was taken into protective custody. And then, on 9 May 2005, Ice, the agency that had cherished him, decided that his US visa was irregular and began legal proceedings to deport him to Mexico - without doubt a death sentence. He is now in a maximum-security jail in the Midwest, fighting his former employers through the courts. In October The Observer won clearance to visit him with his lawyer, Jodi Goodwin. On the eve of the interview he was abruptly moved to a different facility where officials said a visit was impossible. Goodwin passed on a message: 'I'm not mad, I'm sad and disillusioned. Every time I did a job and brought them information, I was congratulated. Now they want to deliver me to my death.'

'If Congress and the media start to look at this properly, they will be horrified,' Sandy Gonzalez says. 'It needs a special prosecutor, as with the case of Valerie Plame [the CIA agent whose name was leaked to the media when her diplomat husband criticised Bush over Iraq's missing weapons of mass destruction]. But Valerie is a nice-looking white person and the victims here are brown. Nobody gives a shit.'

For the three children who lost their father, and their mother, now struggling to make ends meet, it is difficult to cope. 'It's worst at night, when I put them to bed,' Janet Padilla says. 'I guess that's when it hits them. I tell them, "come on you guys, we got to make a prayer. Don't worry. Your daddy's watching you." But you know, it's very hard to make it as a dad as well as a mom.'

The Associated Press reported Thursday that Americans and foreigners crossing U.S. borders since 2002 have been assessed by the
Homeland Security Department's computerized Automated Targeting System, or ATS.

The travelers are not allowed to see or directly challenge these risk assessments, which the government intends to keep on file for 40 years. Some or all data in the system can be shared with state, local and foreign governments for use in hiring, contracting and licensing decisions. Courts and even some private contractors can obtain some of the data under certain circumstances.

"It is simply incredible that the Bush administration is willing to share this sensitive information with foreign governments and even private employers, while refusing to allow U.S. citizens to see or challenge their own terror scores," Leahy said. This system "highlights the danger of government use of technology to conduct widespread surveillance of our daily lives without proper safeguards for privacy."

The concerns spread beyond Congress.

"I have never seen anything as egregious as this," said Kevin Mitchell, president of the Business Travel Coalition, which advocates for business travelers. It's "evidence of what can happen when there isn't proper oversight and accountability."

By late Friday, the government had received 22 written public comments about its after-the-fact disclosure of the program last month in the Federal Register, a fine-print compendium of federal rules. All either opposed it outright or objected to the lack of a direct means for people to correct any errors in the database about themselves.

"As a U.S. citizen who spends much time outside the U.S., I can understand the need for good security," wrote one who identified himself as Colin Edmunds. "However, just as I would not participate in a banking/credit card system where I have no recourse to correct or even view my personal data, I cannot accept the same of my government."

Privacy advocates also were alarmed.

"Never before in American history has our government gotten into the business of creating mass 'risk assessment' ratings of its own citizens," said Barry Steinhardt, a lawyer for the
American Civil Liberties Union. "We are stunned" the program has been undertaken "with virtually no opportunity for the public to evaluate or comment on it."

The Homeland Security Department says the nation's ability to spot criminals and other security threats "would be critically impaired without access to this data."

And on Friday as the normal daily flow of a million or more people entered the United States by air, sea and land, the ATS program's computers continued their silent scrutiny. At that Virginia building with no sign, the managers of the National Targeting Center allowed an Associated Press photographer to briefly roam their work space.

But he couldn't reveal the building's exact location. None of the dozens of workers under the bright fluorescent lights could be named. Some could not be photographed.

The only clue he might have entered a government building was a montage of photos in the reception area of
President Bush's visit to the center. But there was only one guard and a sign-in book.

Inside, red digital clocks on the walls showed the time in Istanbul, Baghdad, Islamabad, Bangkok, Singapore, Tokyo, and Sydney. Although billboard-size video screens on the walls showed multiple cable news shows, there was little noise in the basketball-court-sized main workroom. Each desk had dual computer screens and earphones to hear the video soundtrack. Conferences were held in smaller workrooms divided by glass walls from the windowless main room.

Round the clock, the targeters from Homeland Security's Customs and Border Protection agency analyze information from multiple sources, not just ATS. They compare names to terrorist watch lists and mine the Treasury Enforcement Communications System and other automated systems that bring data about cargo, travelers and commercial workers entering or leaving the 317 U.S. ports, searching for suspicious people and cargo.

Almost every person entering and leaving the United States by air, sea or land is assessed based on ATS' analysis of their travel records and other data, including items such as where they are from, how they paid for tickets, their motor vehicle records, past one-way travel, seating preference and what kind of meal they ordered.

Government officials could not say whether ATS has apprehended any terrorists. Based on all the information available to them, federal agents turn back about 45 foreign criminals a day at U.S. borders, according to Homeland Security's Customs and Border Protection spokesman Bill Anthony. He could not say how many were spotted by ATS.

Officials described how the system works: applying rules learned from experience with the activities and characteristics of terrorists and criminals to the traveler data. But they would not describe in detail the format in which border agents see the results or in which the databases store the results of the ATS risk assessments.

Acting Assistant Homeland Security Secretary Paul Rosenzweig told reporters Friday they could call it scoring. "It can be reduced to a number," he said, but he clearly preferred the longer description about how the rules are used.

"I've never heard of anybody doing that," said George Wright, chairman of the Criminal Justice Department at Santa Ana College. "You're using someone else's property, and that can lead to other problems. ... What if someone forgets about the gun and just leaves it behind?"

Police in Las Vegas abandoned a similar training tactic for drug-sniffing police dogs last year, when a man was falsely charged with drug possession after a canine officer forgot to retrieve drugs planted in the man's car, according to published reports.

Still, Small said the exercises teach newer officers how to search vehicles in realistic situations.

Performing the exercise in a parking lot with a police vehicle would not be as effective because the officers would be expecting to find contraband, he said. The training is usually done after suspects are arrested and the cars are being readied for impound, Small said.

But Cox said he was feet away from Officer Brian Knorr that January evening when Knorr flung the gun into the trunk.

"I was thinking, 'what the hell is this?'" said Cox, a 45-year-old construction superintendent. "I thought I was going to get a weapons charge. I thought I was going to get my ass kicked."

An officer found the gun minutes later, Cox said.

"That's not my gun!" Cox said he shouted.

Cox had been pulled over by police after a witness said he saw Cox hit another vehicle and flee the scene.

Cox said he was never told the officers were performing a training exercise.

He filed a complaint with the police department in August against Knorr and another officer, who he said barreled questions at him and called him names like "Slick.''

Several officers testified about the incident during Cox's October trial. Knorr testified that he planted the loaded gun because he "saw an opportunity to create a realistic search of a vehicle."

He said he and another officer "had a little chuckle" that night because the gun was found by a veteran police officer instead of the intended subject of the exercise.

Cox was convicted of hit and run, driving without a license, driving under the influence, reckless driving and possession of marijuana. He awaits sentencing Dec. 15.

Last month he received a letter from the police department saying the officers in his complaint had been "exonerated" of wrongdoing.

Small said Friday that using a loaded weapon during training - as Knorr testified he had done - is against department policy, and that performing the exercise in front of Cox "could have been done in a better way."

But he said Knorr was exonerated because the policy was not widely understood.

"I didn't feel comfortable holding one officer accountable for it when others were doing it as well," Small said. "I think the department did something wrong because we didn't make sure people understood what our policy really was."

The department doesn't have a formal protocol for using the public's vehicles in training exercises, department spokesman Lt. Craig Junginger said. However, vehicle owners typically aren't told their cars are being used for training because they're not usually present when the training occurs, Small said.

The training exercises are "designed to be very controlled situations, planned ... and discussed with a supervisor in advance,'' Small said.

Ed Pecinovsky, bureau chief of training for the state's commission on Peace Officer Standards and Training, said that no matter how careful officers are, using an arrestee's car in a training exercise is "asking for problems."

Cox said he's considering a lawsuit.

"This is police abuse," he said. "Huntington Beach used to be my dream home. Now, I'm moving away."

A federal appeals court in Richmond, Va., heard arguments Tuesday by el-Masri's lawyers urging the judges to reinstate his lawsuit against a former CIA director, George Tenet, and others.

Discussing the case, el-Masri told reporters, ''What really matters to me is that I would like to know why this was done to me, and I want an explanation and an apology.''

He added, ''I think that we can all benefit from what happens in my case, including others who are still in prison in other parts of the world without the rule of law.''

El-Masri alleges he was kidnapped while trying to enter Macedonia for a vacation on Dec. 31, 2003. He claims he was flown to a CIA-run prison known as the ''salt pit'' in Kabul, Afghanistan, where he was beaten and sodomized with an object during five months in captivity.

''The conditions that I was confronted with were not fit for a human,'' he told reporters. He said his food was barely edible and the water putrid.

''It was like water you left in an aquarium for years,'' he said. ''When you took one sip, the taste stayed in your mouth for hours.''

The CIA has refused to comment on el-Masri's allegations, which have put a spotlight on the intelligence agency's secret program to deliver suspected terrorists for interrogation in foreign countries. The practice has been heavily criticized by human rights groups.

El-Masri's suit was dismissed in May when a judge ruled that a trial could harm national security by revealing details about CIA activities.

El-Masri said that despite the setback, he had confidence in the courts and the U.S. justice system. He previously was denied entry into the United States when he arrived to publicize the filing of his suit last year, according to the American Civil Liberties Union, which has supported his case. In recent weeks, he was issued a visa.

ACLU lawyer Ben Wizner told the appeals court on Tuesday that el-Masri was ''the public face of a publicly acknowledged program'' whose basics generally have become known. Thus, the lawyer said, the case could be considered without exposing government secrets.

Justice Department lawyer Greg Katsis argued that the government properly invoked its state secrets privilege to protect information outlined in a classified affidavit that Judge T.S. Ellis III read before dismissing the suit

El-Masri's allegations also are the subject of a German parliamentary investigation that is trying to clarify when German government officials became aware of el-Masri's case and whether German security services participated in interrogations in Afghanistan.

The appeals court usually takes several weeks to issue its ruling.

Several guards in camouflage and riot gear approached cell No. 103. They unlocked a rectangular panel at the bottom of the door and Padilla's bare feet slid through, eerily disembodied. As one guard held down a foot with his black boot, the others shackled Padilla's legs. Next, his hands emerged through another hole to be manacled.

Wordlessly, the guards, pushing into the cell, chained Padilla's cuffed hands to a metal belt. Briefly, his expressionless eyes met the camera before he lowered his head submissively in expectation of what came next: noise-blocking headphones over his ears and blacked-out goggles over his eyes. Then the guards, whose faces were hidden behind plastic visors, marched their masked, clanking prisoner down the hall to his root canal.

The videotape of that trip to the dentist, which was recently released to Padilla's lawyers and viewed by The New York Times, offers the first concrete glimpse inside the secretive military incarceration of an American citizen whose detention without charges became a test case of President George W. Bush's powers in the fight against terror. Still frames from the videotape were posted in Padilla's electronic court file late Friday.

To Padilla's lawyers, the pictures capture the dehumanization of their client during his military detention from mid-2002 until earlier this year, when the government changed his status from enemy combatant to criminal defendant and transferred him to the federal detention center in Miami. He now awaits trial scheduled for late January.

Together with other documents filed late Friday, the images represent the latest and most aggressive sally by defense lawyers who declared this fall that charges against Padilla should be dismissed for "outrageous government conduct," saying that he was mistreated and tortured during his years as an enemy combatant.

Now lawyers for Padilla, 36, suggest that he is unfit to stand trial. They argue that he has been so damaged by his interrogations and prolonged isolation that he suffers post-traumatic stress disorder and is unable to assist in his own defense. His interrogations, they say, included hooding, stress positions, assaults, threats of imminent execution and the administration of "truth serums."

A Pentagon spokesman, Lt. Col. Todd Vician, said Sunday that the military disputes Padilla's accusations of mistreatment. And, in court papers, prosecutors deny "in the strongest terms" the accusations of torture and say that "Padilla's conditions of confinement were humane and designed to ensure his safety and security."

"His basic needs were met in a conscientious manner, including Halal (Muslim acceptable) food, clothing, sleep and daily medical assessment and treatment when necessary," the government stated. "While in the brig, Padilla never reported any abusive treatment to the staff or medical personnel."

In the brig, Padilla was denied access to counsel for 21 months. Andrew Patel, one of his lawyers, said his isolation was not only severe but compounded by material and sensory deprivations. In an affidavit filed Friday, he alleged that Padilla was held alone in a 10-cell wing of the brig; that he had little human contact other than with his interrogators; that his cell was electronically monitored and his meals were passed to him through a slot in the door; that windows were blackened, and there was no clock or calendar; and that he slept on a steel platform after a foam mattress was taken from him, along with his copy of the Koran, "as part of an interrogation plan."

Padilla's situation, as an American declared an enemy combatant and held without charges by his own government, was extraordinary and the conditions of his detention appear to have been unprecedented in the military justice system.

Philip D. Cave, a former judge advocate general for the Navy and now a lawyer specializing in military law, said, "There's nothing comparable in terms of severity of confinement, in terms of how Padilla was held, especially considering that this was pretrial confinement."

Ali al-Marri, a Qatari and Saudi dual citizen and the only enemy combatant currently detained in the United States, has made similar claims of isolation and deprivation at the brig in South Carolina. The Pentagon spokesman, Lieutenant Vician, said Sunday that he could not comment on the methods used to escort Padilla to the dentist. Blackened goggles and earphones are rarely employed in internal prison transports in the United States, but riot gear is sometimes used for violent prisoners.

One of Padilla's lawyers, Orlando Do Campo, said, however, that Padilla was a "completely docile" prisoner. "There was not one disciplinary problem with Jose ever, not one citation, not one act of disobedience," said Do Campo, who is a lawyer at the Miami federal public defender's office.

In his affidavit, Patel said, "I was told by members of the brig staff that Padilla's temperament was so docile and inactive that his behavior was like that of 'a piece of furniture.' "

Federal prosecutors and defense lawyers are locked in a tug of war over the relevancy of Padilla's military detention to the present criminal case. Federal prosecutors have asked the judge to forbid Padilla's lawyers from mentioning the circumstances of his military detention during the trial, maintaining that their accusations could "distract and inflame the jury."

But defense lawyers say it is unconscionable to ignore Padilla's military detention because, among other reasons, it altered him in a way that will impinge on his trial.

Dr. Angela Hegarty, director of forensic psychiatry at the Creedmoor Psychiatric Center in Queens, N.Y., who examined Padilla for a total of 22 hours in June and September, said in an affidavit filed Friday that he "lacks the capacity to assist in his own defense."

"It is my opinion that as the result of his experiences during his detention and interrogation, Padilla does not appreciate the nature and consequences of the proceedings against him, is unable to render assistance to counsel, and has impairments in reasoning as the result of a mental illness, i.e., post-traumatic stress disorder, complicated by the neuropsychiatric effects of prolonged isolation," Dr. Hegarty said in an affidavit for the defense.

Padilla's status was abruptly changed to criminal defendant from enemy combatant last fall. At the time, the Supreme Court was weighing whether to take up the legality of his military detention - and thus the issue of the president's authority to seize an American citizen on American soil and hold him indefinitely without charges - when the Bush administration pre-empted its decision by filing criminal charges against Padilla.

Padilla was added as a defendant in a terrorism conspiracy case already under way in Miami. The strong public accusations made during his military detention - about the dirty bomb, Al Qaeda connections and supposed plans to set off natural gas explosions in apartment buildings - appear nowhere in the indictment against him. The indictment does not allege any specific violent plot against America.

Padilla is portrayed in the indictment as the recruit of a "North American terror support cell" that sent money, goods and recruits abroad to assist "global jihad" in general, with a special interest in Bosnia and Chechnya. Padilla, the indictment asserts, traveled overseas "to participate in violent jihad" and filled out an application for a mujahedin training camp in Afghanistan.

Michael Caruso, a public defender for Padilla, pleaded "absolutely not guilty" for him to charges of conspiracy and of providing material support to terrorists. Padilla faces two charges that each carry a maximum penalty of 15 years.

Over the summer, Judge Marcia G. Cooke of United States District Court in Miami threw out the most serious charge, of conspiracy to murder, kidnap and maim persons in a foreign country, saying that it replicated accusations in the other counts and could lead to multiple punishments for a single crime. This was a setback for the government, which has appealed the dismissal.

Padilla's lawyers say they have had a difficult time persuading him that they are on his side.

From the time Padilla was allowed access to counsel, Patel visited him repeatedly in the brig and in the Miami detention center, and Padilla has observed Patel arguing on his behalf in Miami federal court.

But, Patel said in his affidavit, his client is nonetheless mistrustful. "Mr. Padilla remains unsure if I and the other attorneys working on his case are actually his attorneys or another component of the government's interrogation scheme," Patel said.

Do Campo said that Padilla was not incommunicative, and that he expressed curiosity about what was going on in the world, liked to talk about sports and demonstrated particularly keen interest in the Chicago Bears.

But the defense lawyers' questions often echo the questions interrogators have asked Padilla, and when that happens, he gets jumpy and shuts down, the lawyers said.

Dr. Hegarty said Padilla refuses to review the video recordings of his interrogations, which have been released to his lawyers but remain classified.

He is especially reluctant to discuss what happened in the brig, fearful that he will be returned there some day, Patel said in his affidavit.

"During questioning, he often exhibits facial tics, unusual eye movements and contortions of his body," Patel said. "The contortions are particularly poignant since he is usually manacled and bound by a belly chain when he has meetings with counsel."