WASHINGTON — More than a dozen current and former prosecutors and lawmakers urged Texas Governor Rick Perry, a Republican presidential candidate, to delay a condemned man's execution to allow for DNA testing.

Henry "Hank" Skinner was sentenced to death for the 1993 triple slaying of his girlfriend, who was beaten to death, and her two sons, who were fatally stabbed. Skinner's execution is scheduled for November 9.

"Executing Mr Skinner without testing all the relevant evidence would suggest official indifference to the possibility of error in this case and needlessly undermine public confidence in Texas's criminal justice system," said the letter signed by 18 current and former elected officials, prosecutors and judges.

"There is simply no justifiable reason why Texas continues to waste taxpayer dollars in its decade-long fight to prevent scientific testing in Mr Skinner's case. We implore you to take the lead in the search for truth in this case."

The letter -- addressed to Perry, Texas Attorney General Greg Abbott and Gray County District Attorney Lynn Switzer -- was even signed by a former Texas governor, Mark White.

Skinner, 48, repeatedly has denied he committed the murders and has pleaded with authorities for over a decade to test DNA he says could prove that someone else killed the trio.

The state has long refused, citing a restrictive state DNA testing law. But lawmakers made changes to the law this year that lifted many of the restrictions.

"That legislation passed with overwhelming bipartisan support, not least because polls show that 85 percent of Texans agree that prisoners should have broad access to DNA testing," the officials said in the letter.

They pointed to the exoneration of Michael Morton this month thanks to DNA tests after 25 years in prison.

Last year, the US Supreme Court granted a stay of Skinner's execution less than an hour before he was due to be put to death. The high court sent the case back to a lower court to rule on Skinner's DNA testing request.

Photo credit: Gage Skidmore