A man has been executed for gunning down a Texas state trooper, a slaying his trial attorneys had argued was prompted by anti-police rap music

Michael Graczyk:

The slain trooper's widow and daughter, who were standing next to the window, hugged and kissed as the 32-year-old Howard slipped into unconsciousness.

"Today justice has been served," said Linda Davidson, widow of Department of Public Safety Officer Bill Davidson. "It's real frustrating the wheels of justice turn very slowly."

Howard was executed for killing the 43-year-old Davidson during a traffic stop outside Edna, about 100 miles southwest of Houston.

At the time of the shooting, Howard, then 18 and a father of four, was on probation for burglary.

Defense lawyers argued at his trial that Howard's constant exposure to gangsta rap music and its anti-police messages influenced him to pull the trigger.

Killer who claimed to be influenced by rap music faces execution Thursday