I would assume it be the Police (as mentioned). They're government workers who need access to every part of the city. It appears to be relatively rare otherwise. Also, because everyone seemed to miss what I had said: This combos in well with one of the police records about there being a call starting around 8:51. The Sudoku puzzle rounded out to 8:52, a minute ahead. It's probable there may be a relationship there. It may not be Philter, though.

Also, can someone with a Lockpick skill (or fighting type abilities) go pick that lock with the live Pokemon inside it? that's probably important.