How many times have you responded to a commercial alarm and found that the business door was left unlocked by the employees or cleaners? You might have to wait for someone to respond to lock the door. This is a little trick I use to lock doors that have an interior turn latch--with the help of some crime scene tape--so you can secure it yourself.
1. Determine which way you need to turn the latch to get the locking mechanism to extend into the door jamb.
2. Take some crime scene tape and wrap it so when you pull it, it will turn the latch the way you need it to go. Make sure you have enough to grab onto from the outside of the door.
3. Position the latch so that you need to only turn it a little to throw the lock into the jamb.
4. Close the door and pull on the tape from outside the business. Hopefully this will throw the bolt into the jamb, securing the door.
5. Now you can leave the business knowing that the door is secure.