Mortise lock

While doing maintenance at one of my schools buildings I came across a door that had what I think is a mortise lock. It has a spot for a key on the outside but no way of unlocking the bolt from the inside. It seems to me that the handle is the only part that locks but isnt attached like other photos of mortise locks. I can open the door by turning the handle on the inside but as soon as someone closes the door we're locked out again. We've been taking turns climbing through the window whenever someone closes it but that gets old fast. Is this lock pickable and if so is it easy? Also the lock had a logo that was three: ^ all in a row under each other.