Jack considers how to answer this for a moment. The only people he's told about his "officially dead" status are those he knows from CTU; those that thought he was going to die on that day in April. He's never actually told it to someone not from his world, and he's not sure he really wants to.

"I left, both for my own reasons and reasons out of my control," he says smoothly. Which is something vaguely like the truth, but also completely off base.