Arizona to Execute Second Inmate in 8 Days All known requests to stop the execution of an Arizona death row inmate have been denied, so the plan to carry out a second death sentence in eight days moved ahead Thursday. Robert Charles Towery, 47, was scheduled to be given a lethal injection at 10 a.m. at the state prison in Florence, after spending nearly 20 years on death row for robbing and killing Mark Jones, of Scottsdale. Towery's attorneys made several unsuccessful last-minute arguments in an effort to spare him, including a Wednesday request with the Arizona Supreme Court to reduce his sentence to 25 years to life in prison because Towery's co-defendant spent less than 10 years in prison. Randy Allen Barker, the other man convicted in the killing, was given a plea deal for testifying against Towery and was released from prison in 2001. Towery's lawyers argued that although Towery strangled Jones, Barker was holding the gun, watched the prolonged killing and "exhibited extreme indifference to human life." "Mr. Barker was present while Mr. Towery choked Mr. Jones, walking in and out of the bedroom," according to the filing. He could have stopped Mr. Towery. ... Mr. Towery was unarmed, and had neither physically assaulted nor threatened Mr. Barker. Given Barker's lenient sentence, putting Towery to death would be grossly disproportionate, the attorneys argued. FILE - This undated file photo provided by the Arizona Department of Corrections shows death-row inmate Robert Charles Towery. The Arizona Supreme Court has turned down a last-minute mercy request from Towery, who is set to be executed on Thursday, March 8, 2012. Towery has been on death row for nearly 20 years for killing Mark Jones of Scottsdale while robbing his home. (AP Photo/Arizona Department of Corrections, File) Close The court turned them down less than two hours after receiving the filing. The U.S. Supreme Court also denied a review of the case and a stay of execution. The attorneys said that after the killing, both men disposed of Jones' car, split the cash they had stolen, and that Barker gave most of the stolen items to family and friends. In other filings, Towery's attorneys argued that the trial court failed to consider so-called mitigating factors that merited a sentence of life in prison over the death penalty, including an extremely difficult childhood that included abuse at the hands of his mother and longtime drug abuse. Towery himself asked the state's clemency board last week to show him mercy and give him a sentence of life in prison. He also apologized to Jones' family for killing him. "I have the deepest regrets for what I did and I'm truly sorry for their loss, for what I did to them," he said. It's a terrible thing that I did and it should never have happened. ... I can only pray that they will find peace and that someday they'll be able to forgive me. He said that he and Barker decided to rob Jones because Towery knew he had money and that they discussed killing him beforehand. At Towery's trial, the state's case rested on Barker's testimony. Barker testified that he and Towery had discussed robbing Jones for several weeks before they went to his home on Sept. 4, 1991, with a made-up story that their car had broken down and they needed to use his phone. Jones, who had met Towery before, agreed. Barker said that Towery then pulled a gun on Jones and Barker handcuffed him. The two loaded Jones' Lincoln Continental with electronics, jewelry, credit cards and cash from the home, before they took him to his bedroom at gunpoint. Towery had Jones lay face-down with his hands tied behind his back and then tried to inject his arm with battery acid, Barker said. When that had no apparent effect, Towery then made a noose out of plastic ties and tried to strangle Jones, Barker testified.