I've been working on multilinked panic buttons for no real reason -- guess now they've got a purpose. If I could get them distributed to all the people keeping a lookout, we could make the whole process easier by far. If one of us sees him, we could use the button, and it would send a signal to the rest of us. It's virtually untraceable by outside sources. The only real risk I could see to it is if one would fall into the wrong hands.
Ask around, see if anyone would go for the idea. My brothers and I used something like these to keep an eye on the entire city when we did our patrols.