Superintendent Mike Keating of the Queensland police said while the coroner in Cairns continues autopsy proceedings, investigators had reviewed the video.
"There is no evidence that Mr. Irwin was intimidating or threatening the stingray,'' he said. "My advice is that he was observing the stingray. There are no suspicious circumstances in relation to the death of Mr. Irwin.''
Irwin and his crew were in shallow waters off northern Australia Monday morning when the large stingray's barb punctured Irwin's heart.
Meanwhile in Parliament, Prime Minister John Howard said the 44-year-old known internationally as "The Crocodile Hunter" died in "bizarre, tragic and in some respects quintessentially Australian circumstances," the Sydney Morning Herald reported.
No funeral arrangements have been announced yet, but Queensland State Premier Peter Beattie said Irwin would be given a state funeral if his family approved, the BBC reported.