"There is no question he was hypno-programmed," lawyer William F. Pepper told ABCNews.com. "He was set up. He was used. He was manipulated."
Sirhan will appear before a California parole board on Wednesday for the 14th time since his May 1969 sentencing. It is the first time he will be represented by Pepper.
Taking a page from the conspiracies that have dogged the assassination of Kennedy's brother President John F. Kennedy, Pepper plans to introduce new evidence that suggests there was a second gunman who fatally shot RFK in the kitchen of a Los Angeles hotel, following his victory in the 1968 California presidential primary.
Pepper said he believes Sirhan was "hypno-programmed," essentially brainwashed to kill Kennedy and his memories were then erased.
A lawyer for Sirhan Sirhan, the confessed assassin of Robert F. Kennedy, plans to present new evidence at a parole board hearing suggesting that he did not act alone, was potentially brain washed and cannot remember anything about the 43-year-old shooting.
The lawyer's tale has all the makings of a great conspiracy theory, if not a science fiction thriller akin to the "Manchurian Candidate."
"Ten independent witnesses say Sirhan was always in front of Bobby, never behind him," said Pepper, "but the autopsy says Bobby was shot at close range from behind the right ear."
Pepper says he believes he knows who ordered Sirhan to shoot Kennedy, but won't yet say who it is. He said in addition to the parole hearing, he is preparing an appeal.
Pepper said Sirhan is "remorseful" for his role in the 1968 assassination of Kennedy, but the gunman "does not remember anything about the shooting."
The image of Sirhan sitting in a California prison cell in 2011 regretting a crime he does not remember does not jibe with a defiant Sirhan sitting a California courtroom in 1969.
At his trial, Sirhan confessed to the crime and declared he had committed it "with 20 years of malice aforethought."
Members of the Kennedy family declined to discuss the claims by Sirhan's lawyer.
The second gunman theory is not new, said Cyril Wecht, a renowned forensic pathologist and one of two independent physicians who examined Kennedy's body. Wecht was also one of nine forensic pathologists on a panel who reexamined the JFK assassination, but the only one who dissented from the single bullet theory.
Wecht said the coroner in the RFK case gave "unchallenged, unequivocal" testimony to the grand jury that Kennedy had been shot from behind at close range. Witnesses all put Sirhan in front of Kennedy.
Wecht said it was scientifically plausible to hypnotize someone and induce them to murder, but said he did not know if there was enough evidence to suggest that in Sirhan's case.
Parole hearings are typically not the platform to introduce new evidence, or retry a case. Boards typically want to hear convicts express remorse for their crimes, not deny remembering them.
But Pepper says "There is an exception when the factual narrative is wrong. Counsel has the right to correct those facts. I don't know why prior counsel never did that. I am going to clarify the record."
A spokeswoman for the California Department of Corrections and Rehabilitation said she cannot comment on the specifics of Sirhan's case, but parole board hearings generally "are not to decide guilt or innocence."
"The board accepts as fact the guilty verdict," said Terry Thornton. "The purpose is to determine if or when an inmate can return to society."
Pepper successfully won a 1999 civil case against the city of Memphis, in which he argued Memphis police were involved in the assassination of Martin Luther King Jr., for which James Earl Ray, the only suspect was convicted in 1969.
Pepper said Sirhan had been examined by Daniel Brown, a psychologist on the faculty of Harvard Medical School, who found he was "easily hypnotized" and was not faking his inability to remember the crime.
Kennedy's Bodyguard Remembers
Sirhan might not remember what took place in the kitchen of L.A.'s Ambassador Hotel on June 14, 1968, but history has not forgotten.
Kennedy, then a U.S. senator from New York, was making his way through the hotel's kitchen soon after winning the Democratic primary. Sirhan entered the kitchen, fired on Kennedy and was soon subdued as bodyguards smashed his hand against a steam table. Sirhan continued to fire, emptying all the bullets in his pistol from his immobilized hand as bullets ricocheted around the kitchen.
Rosey Grier, a former NFL player who had joined Kennedy's security team, entered the kitchen just after the shots were fired and helped subdue Sirhan.
Grier told ABC News.com that he didn't know for sure if Sirhan acted alone. But, he said: "All I know is that he was the man who had the gun. I took the gun out of his hand. He was that man. Evidence wise, I believe police did their job in finding out where the bullet came from."
Grier said Sirhan had "a right to do what he has to get justice," but would not comment on whether he believed Sirhan had been hypnotized, or was worthy of parole.
Brown was travelling and could not be reached by ABCNews.com for comment.
"[Sirhan] has whole blocks in his mind that are missing," Pepper said. "He doesn't remember anything,
...the Greenbaum speech here [Link]exert below.
"Then I decided to do a survey, and from the ISSMP&D [International Society for the Study of Mulptiple Personality and Dissociation] folks I picked out about a dozen and a half therapists that I though were seeing more of that than probably anyone else around and I started surveying them. The interview protocol, that I had. got the same reaction almost without exception. Those therapists said, "You're asking questions I don't know the answers to. You're asking more specific questions than I've ever asked my patients." Many of those same therapists said, "Let me ask those questions and I'll get back to you with the answer." Many of them not only got back with answers, but said, "You've got to talk to this patient or these two patients." I ended up doing hundred of dollars worth of telephone interviewing.
What I came out of that was a grasp of a variety of brainwashing methods being used all over the country. I started to hear some similarities. Whereas I hadn't known, to begin with, how widespread things were, I was now getting a feeling that there were a lot of people reporting some similar things and that there must be some degree of communication here. "