U.S. inmate dies after failed lethal injection

A UNITED States death row inmate in Oklahoma died of a heart attack after his execution was halted because the lethal injection of three drugs failed to work properly. The execution of Clayton Lockett, 38, was halted after 20 minutes, when one of his veins ruptured, preventing the drugs from taking full effect. The execution of a fellow inmate, due two hours later, was postponed. Both men had unsuccessfully challenged a state law that shields the identities of companies supplying the drugs. It comes amid a wider debate over the legality of the three-drug method and whether its use violates guarantees in the U.S .constitution "against cruel and unusual punishment". Lockett was sentenced to death for the 1999 shooting of a 19-year-old woman. A spokesman for the Oklahoma Department of Corrections told reporters that Lockett had died of a heart attack following the injection of three lethal drugs. "We believe that a vein was blown and the drugs were not working as they were designed to. The director ordered a halt to the execution," spokesman Jerry Massie said.