Gov. Rick Perry (search) blocked the execution of a woman two hours before she could have been put to death for the slayings of her husband and two young children, a move that will allow for more testing of forensic evidence (search).

Frances Newton, 39, would have been the first black woman and the fourth female put to death in Texas since the Civil War (search). She has denied any involvement in the slayings.

On Wednesday, Perry granted her a four-month reprieve a day after the Texas parole board, in a rare step, recommended it. The board usually turns aside requests from condemned prisoners.

"I see no evidence of innocence," Perry said in a statement, but that he granted the "additional time for retesting of gunpowder residue on the skirt the defendant wore at the time of the murders and of the gun used in the murders" using new technology.

Newton was convicted in the 1987 shooting deaths of her husband and two children, ages 20 months and 7. Prosecutors said Newtown killed her family to collect $100,000 in insurance benefits.

Newton, held in a small cell adjacent to the death chamber, smiled when she was told of the reprieve. "I was hopeful someone would hear us," she said. "I'm relieved for my family."

Her lawyers said if the governor had refused their request for a delay, they would have made a last-minute appeal to the Supreme Court.

Prosecutors said Newton's claims contained nothing new.

"Obviously, our office did not think it was necessary to have a 120-day reprieve. But we will go forward with the case just as any other," said Roe Wilson, a Harris County prosecutor.

Newton would have been the 24th Texas inmate executed this year. Nationally, she'd have been the 11th woman executed and the first since a woman was executed in Florida in 2002.