Only flaw I see with that is that animating the dead requires some value of gem, the cheapest being a 25g value one- kinda hard to find in jail. Other than that, even the most low-end version of animate dead requires being third level to get access to it.
Sujurak can Mage Hand at will- if ever the key gets left unattended, then he can pluck it, though I'm not counting on that. Killing another inmate might be a good way to create a chance to act, but I think that their guard would be up if anything if they had the key out near the prisoners. Only thing it would do for sure is get the person with the key to come closer, it wouldn't get their defences down.