Here is an unusual story about a simple control failure:

Police in Germany had to call in a locksmith to break into jail when the lock on a cell broke, trapping a prisoner inside, authorities said Wednesday.

Police in the Bavarian town of Zwiesel near the Czech border locked up the 18-year-old at the police station after he was accused of smashing a car window during May day festivities on Tuesday.

I guess it is fortunate there was no immediate danger to the prisoner. Wonder what kind of lock it was and why/how there was no emergency override options. Was it a design failure?