If I understand you correctly then you're asking two intertwined questions.
- How would technology be utilized to keep prisoners in check?
How could war technology be applied to prisoners
Criminality is a symptom, a symptom of what exactly? A totalitarian regime could paint it as a symptom of madness or some other disease which sounds nasty. Brain reading is possible so the regime could implant the prisoners with a device that will give them great pain or even kill them if they commit another crime. To the outside world, they portray it as 'curing criminals', because seriously who would commit a crime if they immediately go through the most horrendous pain afterwardsafterward? Unknown to the general public is that the prisoners are treated as slaves of the regime; if they step out of line then the implant is activated to punish them accordingly.
So what would we make our scientists do to improve this? There'sThere are several possibilities depending on what kind of war tech the regime wants. One could attempt to create biological warfare infantry. For example, use a trigger in the device that releases a deadly virus (quite probably killing the carrier in the process). If the regime is looking for more subtle war tech then a communication device that transmits directly from brain to brain (i.e. telepathy) can be used to: (1) help communication in the field, and (2) let prisoners know that they are watched. Everywhere. At any time.