Is it illegal not to report a crime?

A recent case in the Valley where Alaska State Troopers said a sexual assault was captured on a cell phone is raising the question of whether it’s legal to watch a crime and not report it.
John Skidmore, the director of the Criminal Division of the Alaska Department of Law, said that with a few exceptions, it is perfectly legal to watch a crime, even a murder, and not report it to authorities.
As for recording a crime, Skidmore said that in and of itself is not illegal, especially if the w