ICE is suppossed to pick him up within 48 hours. If they don't you can ask the warden of the facility to release him. Often times they don't so you would be forced to file a writ of habeas corpus in Federal Court. the filing fee for the writ is really inexpensive around $5. The problem is that once you file it, the U.S. Attorney will call ICE who will immediately go over and pick him up so it doesn't really resolve anything for you. Sometimes you want him to be held longer if your immigration attorney needs to file certain forms of relief for deportation (if eligible) and needs time to do this.