A couple of times, when I've been tasked with locating rebel scum within the Death Star, I received a message saying that the hero had escaped my clutches (even though I tracked him down). How can I prevent this from happening?

A couple of times, when I've been tasked with locating rebel scum within the Death Star, I received a message saying that the hero had escaped my clutches (even though I tracked him down). How can I prevent this from happening?

You can't. However, the hero eacaping gives you two Bux instead of one (presumably to tighten security), so it's a good thing.
You cannot. However, you still get 1 Bux if they escape. Catching them gives 2.
This changed with the Imperial levels update.