If you're like me and weren't able to use GroungeMunky's map because you don't have the other DLC, try going to World of Wardens and downloading "Easy for escape mode" created by 22213.
It's a very simple map to navigate and you can get just about anywhere without too much trouble. After grabbing a snapshot, I would also make sure to recruit 1-3 inmates as well to try and knockout the "I Want YOU!" achievement as well. Then, as GroungeMunky suggested, simply exit the game and try again. I got most snapshots in a minute or two of playing, some took a little longer as they can appear in locked offices or out front of the prison in the Garbage area.
The only snapshot I was unable to get using this map (that I was aware of) was the Locksmith, which appeared in a 'Security' room with a console for remote doors and CCTVs on a personal map I made. I suggest using a map that you can access a Security room with those consoles or you can download my map, "ta escape" and try for yourself. I fully leveled my convict in RAGE and plowed into the room with six other convicts but I bet you can just open the map in Prison Architect mode and change the 'Security Sectors' to shared or unlocked.
Hope this helps. Let me know if you have any questions.