tinyE: What exactly are my informants doing? :P I hire them, keep them around till they hit 100% coverage, and activate them. So, the go to security, stand there a while, and leave. What am I getting out of them?
if you look around the map, icons of contraband will appear, along with targets for those in danger (sometimes themselves, other snitch types, ex law enforcement etc), occasionally you'll also get tunnels and other info out of them.
theres a thin bar on the suspicion bar that I presume shows how suspect they are to the general populace - if that hits high they suddenly stop having much info of use and its best to segregate them into protective... or they end up dead.
problem with that is, they're then a target for beig protected (or so it seems), so often end up dead anyways - as its really hard to properly segregate them without prior planning, which requires funds, time etc. I'll often begin by secioning off areas of the prison with gates at junctions, then use the deplyment screen to ensure theres some "staff only" barrier preventing them from intermingling - along with a time schedule.
Edit: As to the info icons on the map they bring up when in the office (make sure you're on the intel / informants tab to see it), you can search those prisoners or move them if targeted.