well, if ya name the prisoners in their NAME fields when created
then its easy to add "This setCaptive True" to their INIT fields and
setup a trigger (covering the cell - make it rectangular if needed).
And then in the triggers condition field put:
!(bob in thisList) || !(Rob in thisList) etc. ...
...with the following in the activation field:
bob setCaptive false; Rob setCaptive false (etc.)
so that if any prisoner is trying to escape, they're all
considered dangerous again & will be shot.
(p.s. Bob & Rob being the unitNames of them prissy's right!)
PPS:
off course ya can also setup individual conditions foreach prisoner