Many of the people arrested turned out to be relatives of an illegal immigrant, and sometimes the agents went to an outdated address.
These statements are all code saying that when ICE goes looking for a criminal alien they aren't allowed to arrest anybody, but that alien. When they serve a warrant on a known gang member who is an illegal they can't sweep up the illegal parents, siblings, etc. that happen to reside there.
This $hit just makes me tired as my Grand mother used to say.