Oklahoma executed its fourth death-row inmate since October on Thursday morning, giving Gilbert Ray Postelle a lethal injection for his part in a quadruple murder nearly 17 years ago. Hours after a final meal of 20 chicken nuggets, fries, 2 chicken sandwiches, a cola, and a caramel frappé, Postelle declined to give any last words in the death chamber. At an unsuccessful clemency hearing in December, he had said that he accepted that he was guilty for helping his father fatally shoot four people in 2005. “There’s nothing more that I know to say to you all then I am truly sorry for what I’ve done to all these families,” Postelle, 35, said. The inmate’s attorneys argued against his execution, saying that Postelle’s severe learning disabilities, parental abandonment, and methamphetamine abuse beginning at age 12 should have precluded him from death row. “Only the morally ill execute the mentally ill,” an anti-death penalty advocate said in a statement Thursday, adding that executions were becoming “commonplace” in the state after a six-year moratorium on the practice was ended last year.