Oklahoma executed Raymond E. Johnson on Thursday morning for killing his ex-girlfriend and their daughter in 2007. Photo courtesy of Oklahoma Department of Corrections/Website

May 14 (UPI) -- The state of Oklahoma on Thursday carried out the death sentence of a 52-year-old Tulsa man for the 2007 murder of his ex-girlfriend and their infant daughter, the Sooner State's second execution of the year and the nation's 11th.

Raymond E. Johnson was administered the three-drug cocktail at the Oklahoma State Penitentiary and was declared dead at 10:12 a.m. CDT, Oklahoma Department of Corrections Director Justin Farris said to reporters at a press conference.

Johnson was executed for killing Brooke Whitaker, 24, and their 7-month-old daughter, Kya, on June 23, 2007, in a domestic violence slaying.

Court documents state he bludgeoned Whitaker in the head with a hammer after an argument. He told police he struck her after she grabbed a knife and tried to stab him.