The former Australian Guantanamo Bay detainee, Mamdouh Habib, has threatened to sue New South Wales police after he reported a shooting last week.
Mr Habib claims he was robbed, assaulted and abused by officers, after reporting a double shooting in the Sydney suburb of Granville.
The 50-year-old witnessesed the aftermath of the murder of Bassam Chami and Ibrahim Assad as he drove his son home from work.
Mr Habib says he told police he didn't know who was involved in the shooting, but he and his son were arrested and forced into an eight-hour interview.
He says their clothes and car were also seized for forensic examination.
Mr Habib says he plans on suing for false imprisonment and assault.