The problem is that this country has been taking a tough stance when it comes to illegal immigration. They are holding people for months and months. In this case, the "material witness" issue is not necessarily related to him being an illegal alien. There are rules that allow the prosecution to hold a witness they deem as material to their case if they are fearful that they are a flight risk and ruin their case. Since September 11, 2001, the U.S. has used the material witness statute to detain suspects without charge for indefinite periods of time, often under the rubric of securing grand-jury testimony. This use of the statute is controversial and is currently under judicial review.