The claim comes in legal papers filed by Sirhan's lawyers this week.
They're based on hours of interviews with Sirhan, some with him under hypnosis.
He claims a woman in a polka-dot dress was the controller who led him to fire his gun in the hotel where Kennedy was killed.
Sirhan's lawyers also claim their client was a diversion and another gunman killed Kennedy.
For the first time, Sirhan said under hypnosis that on a cue from the girl he went into "range mode" believing he was at a firing range and seeing circles with targets in front of his eyes.
"I thought that I was at the range more than I was actually shooting at any person, let alone Bobby Kennedy," Sirhan was quoted as saying during interviews with Daniel Brown, a Harvard University professor and expert in trauma memory and hypnosis. He interviewed Sirhan for 60 hours with and without hypnosis, according to the legal brief.
The Associated Press contributed to this report.