Los Angeles ( CNN ) -- A controversial assertion by convicted Robert F. Kennedy assassin Sirhan Sirhan to win his freedom was challenged this week by the California attorney general who said `` overwhelming evidence '' exists against Sirhan 's claims . Sirhan 's attorneys have said that a second gunman actually assassinated Kennedy in 1968 and that Sirhan was hypno-programmed to fire a gun as a diversion . `` In sum , ( Sirhan ) can not possibly show that no reasonable juror would have convicted him if a jury had considered his 'new ' evidence and allegations , in light of the overwhelming evidence supporting the convictions and the available evidence thoroughly debunking ( Sirhan 's ) second-shooter and automaton theories , '' Attorney General Kamala Harris said in federal court papers filed this week . Sirhan , the sole person convicted of killing Kennedy , is seeking a new trial or freedom from his life sentence based on `` formidable evidence '' asserting his innocence and `` horrendous violations '' of his rights , defense attorneys said in federal court papers filed last year . Harris , who is asking a federal court in Los Angeles to dismiss Sirhan 's request , conceded in court papers filed Wednesday that his lawyers may be able to show two guns were involved in Kennedy 's assassination . Kennedy was seeking the Democratic presidential nomination when he was killed . But even if Sirhan 's lawyers can show 13 shots were fired in the Kennedy shooting , Sirhan should n't be released from prison , Harris said . `` The mere possibility that more than one firearm was discharged during the assassination does not dismantle the prosecution 's case '' against Sirhan , the attorney general said in the latest court documents . Harris said Sirhan is relying on acoustic expert Philip Van Praag 's analysis of a tape recording of the Kennedy shooting that concludes 13 shots were fired during the murder and `` demonstrates the existence of a second shooter because ( Sirhan ) only fired eight shots . '' The attorney general argues that even if there were a second gunman involved in the Kennedy shooting , Sirhan has n't proven his innocence . Sirhan `` at most has shown that , according to Van Praag , two guns could be heard firing 13 shots in an audiotape of the shooting , '' Harris said . Authorities have said eight bullets were fired in the kitchen pantry of the former Ambassador Hotel in Los Angeles , with three bullets hitting Kennedy 's body , a fourth passing harmlessly through his suit coat and the rest striking five other victims , who survived . Kennedy , younger brother of the assassinated U.S. President John F. Kennedy , was shot shortly after midnight on June 5 , 1968 , only moments after the presidential candidate had claimed victory in California 's Democratic primary election . He died the next day . Defense lawyers William F. Pepper and Laurie D. Dusek say Van Praag 's analysis of the tape recording shows two guns fired 13 shots -- five more gunshots than Sirhan could have fired from his eight-shot revolver . Sirhan had no opportunity to reload his gun in the pantry . Harris calls Van Praag 's analysis `` pure speculation . '' The recording of the Kennedy shooting was made by freelance reporter Stanislaw Pruszynski . ABC News television videotape of the hotel ballroom , where the senator had just claimed victory in the California primary , shows Pruszynski holding his recording equipment in his left hand while descending a small set of ballroom steps , approximately 40 feet away from the kitchen pantry shooting , and moving towards the pantry during the period when the shots were being fired there , off-camera . Harris said that even if it could be proven `` that a second gunman successfully shot Senator Kennedy , ( Sirhan ) would still be guilty of the charged crimes . '' She said that under California 's vicarious liability law , `` an aider and abettor 'is guilty not only of the offense he intended to facilitate or encourage , but also of any reasonably foreseeable offense committed by the person he aids and abets ' . '' The defense argues Sirhan did not knowingly fire at Kennedy but thought he was shooting at circular targets on a firing range . They contend Sirhan was a victim of hypno-programming by conspirators who programmed him to fire shots as a diversion for the senator 's real killer . For his hypo-programming defense , Sirhan is relying on Daniel Brown , an associate clinical professor in psychology at Harvard Medical School who has interviewed Sirhan for 60 hours over a three-year period , according to defense attorneys . But the attorney general rejected the hypno-programming claim . `` The theory that a person could be hypnotized into planning and committing a murder against his will is a controversial ( if not fantastic ) one and has not been adopted by most of Brown 's peers , including the American Psychological Association , '' Harris wrote . `` Thus , even if ( Sirhan ) could show that some psychologists believe in mind control or hypno-programming , his showing of actual innocence is nevertheless based on a debatable theory that is not universally accepted in the psychology community , '' Harris said . Sirhan , who turns 68 next month , was denied parole at a hearing last year where he once again claimed to have no memory of the Kennedy shooting , an assertion Sirhan has maintained since 1968 .
Convicted assassin Sirhan Sirhan asserts a second gunman killed Robert F. Kennedy . Sirhan was hypno-programmed to fire a gun as a diversion , his attorney says . California 's attorney general says a jury would have convicted him anyway . The evidence against Sirhan is `` overwhelming , '' prosecutor says .