The Client (1994)

A street-wise kid, Mark Sway, sees the suicide of Jerome Clifford, a prominent Louisiana lawyer, whose current client is Barry ‘The Blade’ Muldano, a Mafia hit-man. Before Jerome shoots himself, he tells Mark where the body of a Senator is buried. Clifford shoots himself and Mark is found at the scene, and both the FBI and the Mafia quickly realize that Mark probably knows more than he says.
Original title: The Client (1994)