Frazier said he was basing his statements on the memories of one of his officers who was on the department at the time and had arrested Bishop. He said the records from the case have been missing since at least 1987.
"I don't want to use the word 'coverup,' but this does not look good," he said.
Then-Police Chief John Polio told the Globe in 1986 that Bishop, who was 20 at the time, had asked her mother, Judith, in the presence of her brother how to unload a round from the chamber of a 12-gauge shotgun.
Polio told the Globe that while Amy Bishop was handling the weapon, it fired, wounding Seth Bishop in the abdomen. He was pronounced dead at a hospital 46 minutes after the Dec. 6, 1986 shooting.
"Every indication at this point in time leads us to believe it was an accidental shooting," Polio said at the time.
In an interview at his home this afternoon, Polio, 87, said, "There was no coverup." He said he followed all department procedures and then-District Attorney William Delahunt's office conducted an inquiry and the decision was made not to file charges.
But Frazier said the media had been fed an incorrect story. He said that there was an argument at the home on Hollis Avenue and Amy Bishop had fired three shots, then fled the house and pointed the shotgun at a motorist in an attempted carjack. She was then arrested at gunpoint by officers.