Stilled on a Train

During a train ride, someone is killed: an unnamed father character. WHO IS THE KILLER? Timmy: the child of the killed and inheritor to his fortune? Jimmy Bob: an insane business rival? Killer Robot: a ... killer robot? (There is not much else to say about this one...) James T. Wisters: a greedy man seeking to boost his income? The conductor: the guy who runs the train while waiting for a package from his aunt? Or could it be... YOU!!!! (Ill give you 2 hints: its not you or the conductor.) Pleas...