Killer of NSW Police inspector Bryson Anderson pleads guilty to murder Slain: Inspector Bryson Anderson, whom Mitchell Barbieri has admitted killing. Photo: Kylie Pitt, Hawkesbury Gazette A Sydney man has pleaded guilty on what was to be the first day of his Supreme Court trial to murdering decorated NSW police officer Bryson Anderson. The man's mother has pleaded guilty to manslaughter over the crime, and this has been accepted by prosecutors. Mitchell Barbieri, 21, and his mother, Fiona Barbieri, 47 admitted to their crimes on Wednesday in a courtroom packed with the officer's family and his former police mates Mitchell Barbieri now faces life in jail, as a life sentence is mandatory in cases where a police officer is murdered in the course of his or her duty. Barbieri cried and hugged his mother before standing to enter his guilty plea. Both mother and son had originally been charged with murder over the crime. But the court heard on Wednesday, that the Crown accepted the plea of manslaughter for Ms Barbieri on the grounds that she had been suffering "a substantial impairment brought about by an abnormality of mind." Inspector Anderson was murdered on December 6, 2012, at the Barbieri's Oakville home after police received an urgent call from neighbours to attend the property. It is alleged that, when Inspector Anderson went to the back entrance of the house to negotiate with the pair, he was attacked with a knife by Mr Barbieri, while his mother swung a block hammer at other officers who tried to intervene. The pair will return to court for sentencing next week. Mitchell Barbieri cried and hugged his mother before standing to enter his guilty plea. He acknowledged the "strength and thoroughness" of the police investigation into the murder, the support of the public and those who served alongside Inspector Anderson on the day of his death.