Contacted by CNN for comment, Sirhan lead attorney William Pepper called the alleged FBI alteration of Rhodes-Hughes' story "deplorable" and "criminal" and said it "mirrors the experience of other witnesses."

Other witnesses also mentioned more than eight shots

Law enforcement investigators have always maintained that only eight shots were fired in the RFK assassination, all of them by Sirhan. His small-caliber handgun could hold no more than eight bullets.

But released witness interview summaries show at least four other people told authorities in 1968 that they heard what could have been more than eight shots. The following four witness accounts appear not in FBI reports but in Los Angeles Police Department summaries:

-- Jesse Unruh, who was speaker of the California Assembly at the time, told police that he was within 20 to 30 feet behind Kennedy when suddenly he heard a "crackle" of what he initially thought were exploding firecrackers. "I don't really quite remember how many reports there were," Unruh told the LAPD. "It sounded to me like somewhere between 5 and 10."

-- Frank Mankiewicz, who had been Kennedy's campaign press secretary, told police that he was trying to catch up to the senator when he suddenly heard sounds that also seemed to him to be "a popping of firecrackers." When an LAPD detective asked Mankiewicz how many of the sounds he'd heard, he answered: "It seemed to me I heard a lot. If indeed it had turned out to have been firecrackers, I probably would have said 10. But I'm sure it was less than that."

-- Estelyn Duffy LaHive, who had been a Kennedy supporter, told police that she was standing just outside the kitchen pantry's west entrance when the shooting erupted. "I thought I heard at least about 10 shots," she told the LAPD.

-- Booker Griffin, another Kennedy supporter, told police that he had just entered the pantry through its east entrance and suddenly heard "two quick" shots followed by a slight pause and then what "sounded like it could have been 10 or 12" additional shots.

An analysis of a recently uncovered tape recording of the shooting detected at least 13 shot sounds erupting over a period of less than six seconds. The audiotape was recorded at the Ambassador Hotel by free-lance newspaper reporter Stanislaw Pruszynski and is the only known soundtrack of the assassination.

Audio expert Philip Van Praag told CNN that his analysis establishes the Pruszynski recording as authentic and the 13 sounds electronically detected on the recording as gunshots.

"The gunshots are established by virtue of my computer analysis of waveform patterns, which clearly distinguishes gunshots from other phenomena," he said in an e-mail. "This would include phenomena that to human hearing are often perceived as exploding firecrackers, popping camera flashbulbs or bursting balloons."

Van Praag's Pruszynski recording findings are now a major point of controversy among new evidence being argued between the two sides in the Sirhan federal court case. Harris contends that his findings amount to an "interpretation or opinion" that is not universally accepted by acoustic experts.

CNN initially reported on Van Praag's audio analysis in 2008 and then with additional details in a BackStory segment in 2009.

Shots fired from two different locations

California prosecutors have argued that witnesses heard shots coming from only one location, but Rhodes-Hughes tells CNN that while the first two or three shots she heard came from Sirhan's position several feet in front of her, she also heard gunshots "to my right where Robert Kennedy was."

According to the autopsy report, the coroner concluded that the senator's body and clothing were struck from behind, at right rear, by four bullets fired at upward angles and at point-blank range. Yet witnesses said Sirhan fired somewhat downward, almost horizontally, from several feet in front of Kennedy, and witnesses did not report the senator's back as ever being exposed to Sirhan or his gun.

In his analysis of the Pruszynski sound recording, Philip Van Praag found that five of the gunshots captured in the tape were fired opposite the direction of Sirhan's eight shots. Van Praag also concluded that those five shots -- the third, fifth, eighth, 10th and 12th gunshots within a 13-shot sequence -- displayed an acoustical "frequency anomaly" indicating that the alleged second gun's make and model were different from Sirhan's weapon.

A chance meeting with Robert Kennedy

The path that eventually led Nina Rhodes-Hughes to the Ambassador Hotel kitchen pantry began 2½ years earlier during a chance meeting with Robert Kennedy at NBC-TV studios in Burbank, California. She was being made up for her co-starring role in the daytime drama "Morning Star" when Kennedy suddenly entered the makeup room. The actress was starstruck. "I saw Robert Kennedy and everything else disappeared from view," she said. "There was an aura about him that was very captivating. He kind of pulled you in. His eyes were very deep set and they were very blue. And when you looked at him, you got very drawn in to him."

As Rhodes-Hughes remembers it, the senator had arrived to pre-record an interview on "Meet the Press" and the two discussed political issues while awaiting their separate TV appearances. "Here I am, just an actress in a soap opera, and he took the time to have an in-depth conversation with me," said Rhodes-Hughes, who was then known professionally by her screen name Nina Roman.

As impressed as Rhodes-Hughes was with Robert Kennedy, she says the senator indicated that he himself was impressed with her ability to quickly memorize many pages of TV script. She says he confided to her that he had no such talent himself but that his older brother, the assassinated President John F. Kennedy, had possessed similar skills.

"Our conversation basically was the clincher for me," Rhodes-Hughes told CNN. "I said to him, 'You know, I have followed your career in politics and I really believe in you and I love all the things that you did -- and are trying to do, and propose to do -- and so if ever you declare yourself a candidate for the presidency, I will work for you, heart and soul.' And he smiled and said, 'Well, I don't know if that's going to happen.' And he was very humble and very sweet."

Rhodes-Hughes says that later, in the spring of 1968, shortly after Kennedy announced his candidacy for the presidency, she helped form a campaign support group in Los Angeles called "Young Professionals for Kennedy" and assisted in raising funds for the California phase of the senator's White House bid.

Weeks later, as he claimed victory in the California primary, addressing hundreds of supporters in the Ambassador Hotel's Embassy Room shortly after midnight on June 5, Kennedy paid tribute to the many volunteers, like Rhodes-Hughes, who had assisted his campaign. Referring to his own role during his brother's successful run for the presidency in 1960, Kennedy told them, "I was a campaign manager eight years ago. I know what a difference that kind of an effort and that kind of a commitment makes."

Trying to keep Kennedy from heading to the pantry