On December 7th federal air marshals shot and killed a passenger at Miami International Airport when he claimed to have a bomb in his backpack and then ran away. While I'm sure the officers in question were thinking, "Hell, this is about as clear cut a reason to shoot someone in the back as I'm ever likely to have," there were a few factors that might reasonably have suggested a less lethal course of action.
First among these would probably be the presence of the passenger's wife, screaming that the "bomber" was mentally ill and off his meds. Second, it seems just a tad unlikely that an actual bomber would run from an airplane densely packed with potential victims rather than just exploding his bomb where he stood. While I understand these things can happen quickly, and law enforcement officers are forced to make snap decisions, I must admit that the circumstances were questionably compelling with regard to the use of deadly force -- especially given that the passenger had already passed through security.
But then I realized that it happened in Florida, a state that prides itself on being at the forefront of the battle to reign in Big Government. With this in mind, an possible explanation presents itself. Perhaps in addition to being trained to recognize passengers fitting the profile of a terrorist, marshals based in Florida have been trained to recognize passengers fitting the profile of the chronically ill or disabled. For the cost of a couple of bullets, the marshals could save US taxpayers hundreds of thousands or potentially millions of dollars over the course of time the passenger would otherwise have lived.
In any case, the NYT has an article about it. Check it out and draw your own conclusions.