Here is some more potential evidence to prove my theory. The following is from the '24' official site episode guide for last nights show.
Jack helps the shaking Chappelle from the chopper. The two men walk through the yard. Jack asks Chappelle if there is anyone he wants to talk to before he dies, but Chappelle says no. Jack makes Chappelle get on his knees, and Chappelle begs to be given the chance to take his own life. Although Jack is at first hesitant he hands over his gun. Yet Chappelle is unable to pull the trigger. Jack takes the gun and fires point blank at Chappelle’s head.
At. Doesn't say he killed him. To be continued tomorrow night.