They would be immediately terminated from their program, certainly upon their conviction and likely before.
In terms of making the decision, I can show you the speed with which that can be done. I received a phone call from a warden one day about a prisoner in a witness protection unit who had been making obscene phone calls to young girls. I asked the warden, “Are you certain it is him?” Of course, they listen on tape to the prisoners calling out. He said, “Yes, I am absolutely certain it is him.” Then I said, “Well, then, he is out of the witness protection program.” He was removed from the unit, put into solitary someplace, and then--gone, into another prison.