A woman who witnessed the 1968 assassination of Robert F. Kennedy says she has agreed to testify for Sirhan Sirhan's new defense team.

Nina Rhodes-Hughes insists Sirhan was not the only gunman firing shots when Senator Kennedy was murdered only a few feet away from her at a Los Angeles hotel. She says there were two guns firing from separate positions and that authorities altered her account of the crime.

"What has to come out is that there was another shooter to my right," Rhodes-Hughes has told CNN. "The truth has got to be told. No more cover-ups."

As a federal court has been preparing to rule on Sirhan's current legal challenge to his conviction in the Kennedy murder, Rhodes-Hughes says she has been contacted by Sirhan's lead defense lawyer, New York attorney William Pepper. "He asked me if indeed I would testify that there was another shooter and I said yes, I would," she said. Rhodes-Hughes says she has not been contacted by the California attorney general's office, which represents the other side in the Sirhan federal court case.

Rhodes-Hughes has described for CNN various details of the June 1968 assassination as well as her long frustration with the official reporting of her witness account and her reasons for speaking out 44 years later: "I think to assist me in healing -- although you're never 100% healed from that. But more important to bring justice."

"For me it's hopeful and sad that it's only coming out now instead of before -- but at least now instead of never," said the former Los Angeles resident now living near Vancouver, British Columbia, in Canada.

Sirhan, the only person arrested, tried and convicted in the shooting of Robert Kennedy and five other people, is serving a life sentence at Pleasant Valley State Prison in Coalinga, California.

The U.S. District Court in Los Angeles is set to rule on a request by Sirhan, now 68, that he be released, retried or granted a hearing on new evidence, including Rhodes-Hughes' firsthand account.

At his 1969 trial, Sirhan's original defense team never contested the prosecution's case that Sirhan was the one and only shooter in Kennedy's assassination. Sirhan testified at his trial that he had killed Kennedy "with 20 years of malice aforethought." He was convicted and sentenced to death, which was reduced to life in prison in 1972.

After the trial, Sirhan recanted his courtroom confession.

In recent federal court filings, state prosecutors led by California Attorney General Kamala Harris argued that even if there was a second gunman involved in the Kennedy shooting, Sirhan hasn't proven his innocence and he's still guilty of murder under California's "vicarious liability" law. Sirhan's new legal team disputes Harris' assertion concerning the state statute.

The current battle has prosecutors and Sirhan's lawyers engaging directly the merits of new evidence -- as well as witness recollections such as Rhodes-Hughes' account -- never before argued in court.

The particular clash over Rhodes-Hughes was triggered five months ago by prosecutors under the attorney general when they contended that Rhodes-Hughes had told the FBI she heard no more than eight gunshots during the assassination. In court papers filed in February, Harris' prosecutors argued that Rhodes-Hughes was among several witnesses reporting "that only eight shots were fired and that all these shots came from the same direction."

Three weeks later, Sirhan's lawyers challenged those assertions in a response also filed in federal court in Los Angeles. The defense team led by William Pepper contended that the FBI misrepresented Rhodes-Hughes' witness account and that she actually had heard a total of 12 to 14 shots fired.

"She identified fifteen errors including the FBI alteration which quoted her as hearing only eight shots, which she explicitly denied was what she had told them," Sirhan's lawyers argued in February, citing a previously published statement from Rhodes-Hughes in which she stated, "I heard 12-14 shots, some originating in the vicinity of the Senator [and] not where I saw Sirhan."

The FBI and the California attorney general's office have both declined comment to CNN on the controversy over Rhodes-Hughes' witness account since the matter is now being reviewed by a federal judge.

When the dispute over her account erupted in February, CNN sought out Rhodes-Hughes for comment, eventually locating her in March in the Vancouver area.

Rhodes-Hughes, now 78, told CNN that she was a television actress working as a volunteer fundraiser for Kennedy's presidential campaign and that she had been invited to the Ambassador Hotel to celebrate, along with the senator and hundreds of his supporters, his anticipated victory in the June 4, 1968, California primary election. She said she witnessed the Kennedy shooting shortly after midnight on June 5 inside a hotel kitchen service pantry.

The FBI report indicates that she was indeed inside the hotel pantry during the crucial moments of the Kennedy shooting, but Rhodes-Hughes contends the bureau got details of her story wrong, including her assertions about the number of shots fired and where the shots were fired from.

Rhodes-Hughes tells CNN she informed authorities in 1968 that the number of gunshots she counted in the kitchen pantry exceeded eight -- which would have been more than the maximum Sirhan could have fired -- and that some of the shots came from a location in the pantry other than Sirhan's position.

The 42-year-old Kennedy was the most seriously wounded of the six people shot inside the pantry only moments after the New York senator had claimed victory in California's Democratic presidential primary. The presidential candidate died the next day; the other victims survived.

The Los Angeles County coroner determined that three bullets struck Kennedy's body and a fourth passed harmlessly through his clothing. Police and prosecutors declared the four bullets were among eight fired by Sirhan acting alone.

Rhodes-Hughes told CNN the FBI's eight-shot claim is "completely false." She says the bureau "twisted" things she told two FBI agents when they interviewed her as an assassination witness in 1968, and she says state Attorney General Harris and her prosecutors are simply "parroting" the bureau's report.

"I never said eight shots. I never, never said it," Rhodes-Hughes told CNN. "But if the attorney general is saying it then she's going according to what the FBI chose to put into their report."

"There were more than eight shots," Rhodes-Hughes said. She says that during the FBI interview in her Los Angeles home, one month after the assassination, she told the agents that she'd heard 12 to 14 shots. "There were at least 12, maybe 14. And I know there were because I heard the rhythm in my head," Rhodes-Hughes said. She says she believes senior FBI officials altered statements she made to the agents to "conform with what they wanted the public to believe, period."