Peterboro Mortise lock
Anyways, I had never dealt with something so old before so I was stumped. After a few minutes of repeatedly trying to turn the door handle while simultaneously trying to throw the latch manually it gave. Upon opening it I realized that the set screw which held the mortise lock in place had came lose and wedged itself perfectly against the latch (I set a silver bolt in where the old one was so it would be easier to see).
If anyone could give me a approximate year it would be much appreciated - this thing seems old as dirt.