NEW YORK (AP) — A state trooper had the law on his side when he shot unarmed prison escapee David Sweat, apparently in the back, as the convicted killer ran toward a forest near the Canadian border.State and federal law allows the use of deadly force to prevent an escape if the officer believes the escapee poses a significant threat. Law enforcement experts say this shooting was clear-cut.“There cannot be any cleaner situation than this one,” said Maria Haberfeld, head of the law and police science department at John Jay College of Criminal Justice. “You cannot shoot any fleeing felon, but certainly you can shoot the one who poses a real threat.