McALESTER, Okla.—Oklahoma executed a man Thursday for the 1985 shooting death of an Oklahoma City-area schoolteacher after courts rejected his claim that the state’s lethal injection method would result in unconstitutional pain and suffering. Bigler Stouffer II, 79, received a three-drug lethal injection at the Oklahoma State Penitentiary in McAlester. Stouffer was the first person executed in Oklahoma since John Grant convulsed on the gurney and vomited during his lethal injection in October as the state ended a six-year execution moratorium brought on by concerns over its protocols. Thursday’s execution process that began at 10 a.m. appeared to go more smoothly. After receiving lethal drugs, Stouffer was declared unconscious at 10:07 a.m., and his breaths became shallower at 10:09 a.m. He was declared dead at 10:16 a.m. Oklahoma Attorney General John O’Connor said in statement that the exectuion “was carried out with zero complications.” The Rev. Howard Potts, who was …