The Espinosa paid the price for letting their guards down.
The Espinosa Gang ran roughshod over southern Colorado in the mid 1860s. They claimed that gringos had stolen their land, raped their women, and otherwise treated them badly. So the Espinosas (a family outfit) went on the hunt, reportedly killing at least 32 people over a few months in 1863.
Finally, a kinsman named Tom Tobin (photo) decided to get the reward on their heads. He went to their hideout, got the outlaws drunk—and then cut their throats. He took their heads to authorities, but they only gave Tobin about half the reward.