Facts: A, an illegal alien, drives car from which passenger B fires his handgun at C. A is arrested along with B in May, 2003. A has an ICE (or if you are antiquated, "INS") hold placed on him. He is presumably subject to deportation. Earliest trial date for B is in October. A was initially arrested as having aided and abetted B, but because State does not wish to automatically make him an accomplice witness, A is not indicted. A becomes eligible for release under art. 17.151 sec. 1 (1) from the county jail. Even if served with a subpoena now, it appears unlikely A will be in this country in October and it might well be illegal for him to re-enter the country, even if he were amenable to do so in order to testify about the events leading to B's arrest. Any ideas on how to make use of A's knowledge of the crime? There was a bill in 1997 to authorize taking of depositions by the State, but it did not become law. My guess is people farther south face this type problem all the time.
I am not familiar with it myself, but CCP 39.09 addresses taking of depositions for non-resident witnesses. It doesn't appear to be limited to defense witnesses, but like I said, I've never worked with it.