In an en banc decision, the First Circuit has affirmed District Court decisions finding that the mandatory detention provisions for immigrants with criminal histories only apply if the Department of Homeland Security takes the immigrant into custody at the time he is released from criminal custody. If the person is released from criminal custody and later is taken into immigration custody, he will be eligible to seek a bond from an Immigration Judge.
The full text of Castenada v. Souza can be found here: http://media.ca1.uscourts.gov/pdf.opinions/13-1994P2-01A.pdf