In United States v. Burden, the government failed to show that a witness the government had deposed and then deported was unavailable:
"In a case such as this one, in which the government knew or should have known of the potential need for the witness’s testimony before he was deported, the government’s duty to make good-faith, reasonable efforts to ensure the witness’s presence arises before the witness leaves the United States."
So sayeth the D.C. Circuit. Conviction reversed.