Peter Catalado, a Natick man currently imprisoned for the murder of his sister, was denied parole on Aug. 31.

In a written statement, the parole board wrote Catalado's ongoing symptoms of mental illness are a threat to public safety. 

Catalado was convicted of the shooting his sister, Gina Donaghue, and killing her in 1997 after a long strain on violent and paranoid behavior, the parole board's report said. 

Insisting steroid use was the cause of his mental illenss, Catalano "insisted" he had mentally "returned to normal" during the hearing. 

"There were members of Mr. Catalado's family present in support. There were no attendees who provided testimony in support of his release," the report said.