ICE refers to the United States Immigration and Customs Enforcement, a federal law enforcement agency. If a person is in Pima County Jail in Tucson, for example, or other jail facility in the United States or otherwise in the custody of law enforcement, ICE will request the local agency to
Notify ICE in advance of a scheduled release of the person that ICE has put a hold on.
Hold the person for an additional 48 hours (Not including Saturdays, Sundays or Holidays) to allow time for ICE to take them into custody upon the conclusion/end of their criminal custody.
If a person is able to bond out of jail while in pre-trial custody, they will be transferred to ICE custody. So in essence the person might be released form Pima County Jail or other jail but he or she will not be free from custody. They will simply be in ICE custody instead and have to pursue bond in Immigration Court. If they are bond eligible for their immigration case. They are two separate determinations.
By the same token, if they served there sentence in jail or prison, instead of going home to friends and family , ICE will be there at the end of the term to pick them and place them in ICE custody.
It is also very important to note that just because ICE did not put a hold on the person does not mean they are out of the woods. ICE can swoop in at anytime. ICE holds are just one useful tool they use to apprehend people.
If you believe a loved one or friend is in ICE custody you can search for them by using the ICE detainer locator system. It is not a perfect system but it is a good place to start.