For your consideration ...
I'm not positive of this, but I don't think the Sheriff has anything to say about it. I'm guessing the Commissioners would make those decisions.
Please correct me if I'm wrong.
Sorry. You would be incorrect. This would be a policy of the Sheriff's Office, since it is the Sheriff's Office that ICE deals with regarding illegal alien detainers. Also, when was the last time you ever heard of County Commissioners telling an elected Sheriff how to perform law enforcement operations? Additionally, notice in the list that it specifies the "St. Mary's County Detention Center". For a constitutionally elected office, it seems counterintuitive that a Sheriff would go against the laws he has sworn to protect and enforce. Time for a new Sheriff in St Mary's County.
Now, in a municipality, or city or town with a corporate charter, those
police can be told what to do because they are a department of a municipality, or chartered government, and therefore fall under the control of a mayor, town council, or city council. As far as I understand it.