Members of the NSW Police Force misled the public and their superiors about the 2009 shooting of the mentally ill Sydney man Adam Salter, falsely portraying him as dangerous and psychotic, the Police Integrity Commission has heard.

In the first day of public hearings into allegations that police covered up the true circumstances surrounding the shooting of Mr Salter, 36, counsel assisting the commission, Geoffrey Watson, SC, said that the initial "situation reports" issued by police about the shooting had contained "untrue statements".

Adam Salter, with his father, Adrian, was shot in 2009.

"Within hours of the shooting and in the 48 hours afterwards, the police issued situation reports which were used to explain the circumstances of the shooting to their superiors and the media," Mr Watson said in his opening address.

"These situation reports contained untrue statements and details that portrayed Adam Salter in a negative way. They said he was a dangerous, psychotic man who had come towards them with a knife.