Prison you located in Slovakia is the biggest one and its name is Leopoldov (very nice hires)
The others in SLovakia I know , but not able to locate , are in: Ilava, SK
Trnava, SK (womans prison)
Sabinov, SK (military prison)
You may try to fly there and to locate them (all in Lowres areas).
Maybe there are even more prisons, but there is not an oficcial list of prisons on webpages of the responsible ministry (I was just searching for)