Quote from Captain Stottlemeyer in Mr. Monk and the Missing Granny
Captain Stottlemeyer: A lightning bolt. Lieutenant Disher: Well, we think it's a calling card. There was a radical group in the early '70s. The Lightning Brigade? They were involved in some R.O.T.C. bombings... Captain Stottlemeyer: I know who the Lightning Brigade was, Lieutenant. I remember the '70s. At least some of it.