Sept. 24 (UPI) -- The U.S. government on Thursday carried out the lethal injection of Christopher Vialva for the deaths of a married couple in Texas more than two decades ago, making him the seventh federal execution this year.
The Bureau of Prisons announced the 40-year-old dead at 6:42 p.m. at the U.S. Penitentiary in Terre Haute, Ind.
Vialva was sentenced to death for killing Todd Bagley in 1999 near the Fort Hood Army base in Texas. He also was convicted of killing Todd Bagley's wife, Stacie Bagley, and burning their bodies in their vehicle.
His execution came hours after the Supreme Court declined to issue a stay.
Vialva's attorneys appealed to the high Court this week, saying he received ineffective counsel during his original trial because his lawyers didn't present evidence showing how his age at the time of the crime, 19, may have made him less culpable for the murders.
They also argued that trial attorneys didn't present evidence that Vialva had organic brain injuries and untreated bipolar disorder, or that he had a "dysfunctional upbringing [and] parental neglect." Further, they say, there had been a serious conflict of interest.
"Had the jury heard the extensive mitigation evidence that weighed in favor of sparing Christopher's life, it is very likely that he would not be facing execution today," said appellate attorney Susan Otto.
"Furthermore, the lawyer who was supposed to be defending Christopher's life was, at the same time, applying for a job with the office that was prosecuting Christopher. This clear conflict of interest violated Christopher's right to effective representation.
"Therefore, the question is not whether Christopher should be held accountable for the harm he caused -- no one disputes that. It is whether we can truly call it justice to kill Christopher for a mistake he made as a teenager when he did not get the help or defense everyone deserves."
Defense lawyers cite scientific research that indicates that although the death penalty is outlawed for cases in which the perpetrator is 17 or younger, the brain is still under development into a person's 20s.
The Supreme Court has ruled the death penalty unconstitutional for minors -- 17 and under -- citing research that said juveniles lack the maturity and responsibility of adults, and thus shouldn't be subject to the death penalty.
In a recorded interview with his lawyer, Vialva said he wants a stay not because he's innocent of the Bagley killings, but because he feels like he's been "redeemed."
"I committed a grave wrong when I was a lost kid and took two precious lives from this world. Every day I wish I could right this wrong."
The Death Penalty Information Center says a quarter of all federal death row inmates committed their crimes when they were 21 or younger. Forty-two percent, it notes, were 25 or younger.
U.S. Attorney General William Barr resumed federal executions in July after a 17-year hiatus. Daniel Lewis Lee, Wesley Purkey and Dustin Honken were executed in July; Lezmond Mitchell and Keith Dwayne Nelson in August; and William LeCroy on Tuesday.