Chein said told NBC News on Thursday, "This is a really terrible thing that this individual has been accused of and seems to be admitting guilt to and was convicted of."

But "it's due time for us to really look closely at whether capital punishment can be appropriate for someone who hasn't reached the age of full maturity in their brain, and I'd argue it can't," he said.

Chein said that while a 19-year-old knows the difference rationally between right and wrong, study after study has shown that when you add emotional arousal or social conditions that change the way the brain makes decisions, "it looks like the brain of a younger individual rather than that of a fully matured adult."

...

Vialva pulled out a gun and forced the couple into the trunk, and the group of teenagers drove around for a few hours, stopping to try to withdraw money from the Bagleys' bank account and to pawn Stacie Bagley's ring, according to the Justice Department. Vialva eventually parked at the site of the Fort Hood military reservation and shot the couple while another man set the car on fire, according to the Justice Department.

(http://www.autoadmit.com/thread.php?thread_id=4632785&forum_id=2#40982672)