Blacke's Magic (1986)

Alexander Blacke is a well-renowned magician who after having a near death experience decides to retire but unfortunately retirement doesn't agree with him. So he decides to visit his daughter and father and attend a magician's convention. There a friend of his attempts a stunt wherein he is submerged in a casket underwater. And when he is brought up, he is dead and not from lack of oxygen, but shot. So, Alex helps the police figure out how and why this was done.