After a volunteer confirmed an officer’s identity, they would alert neighbors to the agent’s presence, and our dispatch team would send a text message to our contacts in the area. ICE agents almost never carry judicial warrants giving them the authority to enter private homes or businesses without permission, so they often wait to make an arrest when the person they’re looking for leaves their home or car. And in every case we worked on, when the agents realized they were being watched, they abandoned their stakeout.
That’s a great point. It’s worth going old school in this case for signalling. Word of mouth, visual signals, auditory signals, etc. that are seemingly arbitrary would be a good, though local, way of giving immediate signs.
However, it’s not illegal to monitor and publish that online. If you have the ability, it’s pretty easy to set up a website that has information on their movements. If editing privileges are restricted, you can make a good source of information that is the equivalent of a board saying “ICE reported in the area.” That’s just off of my head, though, so please feel free to poke holes and refine.