When agents encounter strangers, the Fourth Amendment imposes three core limitations:
1. If, and only if, agents have particularized suspicion that a person may be guilty of a crime, they can stop the person (make a "Terry stop") and pose a brief series of questions to dispel or confirm their suspicions. This is the basic dividing line that border czar Tom Homan and others in the administration say the agents are following in nearly every case.
2. If, and only if, agents have developed probable cause that a person is guilty of a crime, they can arrest them -- restrain their physical movements. That includes, of course, Americans or anyone else who assaults law enforcement.
3. At all times, including during arrests, agents may not employ force that is unreasonable under the circumstances.
Now that we are in the age of body worn video cameras, not only should uniformed LEOs be required to wear them, they should state their rationale for the stop (i.e. particularized suspicion and probable cause)
I am sure Epstein didn't have his guests preparing their meals, doing household chores, yard work, etc. It's hard to imagine that the maintenance workers didn't know what was going on. Some enterprising reporters need to visit the place and talk to the workers. There's an interesting story to be told from their perspective ala Downton Abby?