Probably found out he was illegal and took him in. Hire him e best immigration lawyer money can buy, fast! Before its too late..
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
You need to hire an immigration attorney. He can contact the ICE officer in charge of your brother in law's case and see if ICE is willing to accept a bond. If your brother in law has a way to apply for legal status in immigration court and has dependents in the US, there is a very good chance ICE will agree to release him on bond.
This response does not create an attorney client relationship and is for informational purposes only. Before acting on this information you should discuss your problem with an immigration attorney.
It depends on the underlying reason for them holding your brother-in-law. The first step is for you to hire a lawyer. The second step is for you and your lawyer to determine the basis for the hold. Then your lawyer can request a bond with ICE or if ICE refuses then he/she can file a motion for bond redetermination with the immigration judge.