Mexican federal police
© APMay 17, 2011: Mexican federal police stand outside the Goodbar Old West saloon, said to be owned by Bernabe Monje Silva, in Durango, Mexico. Federal authorities claim that the March 27 arrest of Monje Silva led to the discovery of the 219 bodies.
In what has become a string of mass graves discovered in Mexico, law enforcement authorities there have uncovered one of the most gruesome yet.

Eighty-nine bodies were found buried in a vacant auto repair lot in Durango, Mexico. Since April, a total of seven mass graves have been found in the city of almost 600,000, and 308 bodies have been recovered so far.

All the graves have been located in middle-class neighborhoods near schools. Officials say the mass graves probably hold the corpses of executed gang rivals or possibly kidnap victims and even some police. Some of the corpses have been in the ground less than six months, while others have been there for as long as 4 years.

The latest burial site raises question of how residents or authorities could have no knowledge of the graves.

"Something must have failed, maybe intelligence wasn't correct or enough because if we had in place a perfectly designed strategy, situations like those that have occurred, and that have caused so much pain and suffering, would not have happened," said Juan Rosales, the deputy secretary of Durango's Public Safety Department.

There are increasing concerns that the law, which is supposed to protect its citizens, is instead harming them.

Some human rights advocates argue police in Durango may have turned a blind eye to the grim crimes going on in their city, citing a recent case in which 17 corrupt Mexican police were arrested for their alleged involvement in a slaughter last month.

Questions also remain about how the gunmen could have used the burial ground to dump bodies for so long without being caught.

"This happened gradually," said Jorge Antonio Santiago, a spokesman for the Human Rights Commission in Durango. "These are graves of considerable size, so facing this situation we are asking for an explanation. Why didn't they notice?"

Durango's morgue is also overwhelmed by the large number of badly decomposed remains. Morgue officials say it has nowhere to fit them all and had to bring in refrigerated trailers to store piles of bodies awaiting examination, a process that has been slow and painstaking. Forensic specialists, wearing masks and sterile suits, are struggling to identify signs such as tattoos or fingerprints from the bodies that still retained some skin.

Also involved in the identification process are hundreds of families who are taking DNA tests, hoping to find out if any of the dead are their loved ones who violently disappeared months or even years ago. Authorities have only identified one victim so far, a 31-year-old man from the state of Durango. They would not give his name or other details.

In April, the discovery of 183 bodies in 40 graves in the northeastern border state of Tamaulipas caused an international uproar, as families from the U.S., Mexico and Central America showed up in search of loved ones who had been reportedly pulled off buses, then vanished in the vast reaches of farmland near San Fernando, the scene of two mass killings in less than a year.

The Mexican government reinforced its troops there and made a sweep of 74 alleged Zetas members and collaborators, including some local police, whom officials say were responsible for the deaths.

In the past four years, Mexico's bloody drug war has produced almost 40,000 gang-related murders, not including the thousands of missing persons.