Convicted Utah murderer Ronnie Lee Gardner was executed by firing squad late Thursday, becoming the first American put to death that way in 14 years, and only the third since the Supreme Court reinstated the death penalty in 1976. How does execution by firing squad work, and could this increasingly rare execution method be more humane than other ways of carrying out a death sentence? (Watch an AP report about Ronnie Lee Gardner's execution)

How exactly does a firing squad work?
It's not like the movies, with a blindfolded victim in front of a line of riflemen. Instead, the convicted killer is strapped to a chair, with a target pinned over his heart. Five law enforcement officers armed with 30-caliber rifles aim at the target from a distance of no less than 25 feet. All shoot at exactly the same time. One of the guns is loaded with blanks, so that none is certain he fired the fatal shot. The convict can choose whether to wear a black hood; Gardner elected to wear one.

Is this more or less humane than other execution methods?
Death by firing squad has been proven to be a quicker fate than lethal injection, which is Utah's default execution method, reports Daniel B Wood in the Christian Science Monitor. A man shot to death in 1938 while hooked up to a cardiogram showed "complete heart death" within one minute of being shot. Even when carried out correctly, lethal injection takes about nine minutes to kill someone.

What if the shooters miss?
That is extremely unlikely. The executioners are selected for their marksmanship skills, and are given a month to prepare. The chance for error is minimal. Lethal injection, however, has sometimes gone gruesomely wrong. Romell Broom, an Ohio convict, sat on a surgical bed for two hours last September while executioners attempted to find a useable vein into which they could inject the lethal fluid.

Why doesn't the U.S. carry out more executions by firing squad?
Death penalty experts say legislators prefer lethal injection because "it appears dignified and medical," says Margot Sanger-Katz at Slate. Utah started phasing out death by firing squad in 2004 because it gave the state "an image of 'brutality,'" according to one state congresswoman. But it's still an option for inmates like Gardner who were sentenced before the change.

Why was Gardner executed by firing squad?
He chose it. Gardner — sentenced to die for killing a lawyer during a 1985 courthouse escape attempt — had been scheduled to die by lethal injection. Then at an April hearing he told a judge, "I would like the firing squad, please." A controversial doctrine from the early Mormon church holds that killing a person is such a heinous crime that murderers must atone by spilling their own blood on the ground. "I guess it's my Mormon heritage," Gardner told The Deseret News in 1996. "I like the firing squad. It's so much easier... and there's no mistakes."

Sources: Slate, Christian Science Monitor (2), CNN