Material witness holds last as long as the US Marshal needs their testimony. They will hold him on the immigration violation but use his testimony at the trial of the people he was a witness to. In the end he will most likely be deported back to his home country.
https://www.inmateaid.com/ask-the-inmate/how-long-is-a-material-witness-hold-for-an-illegal-immigrant#answer
Accepted Answer Date Created: February 07,2016