This Dec. 1, 2013 photo provided by the Missouri Department of Corrections shows David Zink, who was convicted of abducting and killing 19-year-old Amanda Morton in 2001. (Missouri Department of Corrections via AP)

BONNE TERRE, Mo. - A Missouri man who sexually attacked a 19-year-old woman before tying her to a cemetery tree and killing her was executed Tuesday after the U.S. Supreme Court and the governor declined to intervene.

David Zink, 55, was put to death at a state prison near Bonne Terre, south of St. Louis, hours after the nation's high court rebuffed his last appeals and Gov. Jay Nixon rejected his clemency request. Corrections Department spokesman Mike O'Connell said the lethal injection began at 7:33 p.m. and Zink was pronounced dead at 7:41 p.m.

Zink began breathing haltingly shortly after the injection began. His right hand twitched several times before Zink eventually became motionless.

In a final written statement, Zink said he hoped his execution would bring peace to the family of the woman he killed, Amanda Morton. "I offer my sincerest apology to Amanda Morton's family and friends for my actions."

He added a message to other inmates on death row.

"For those who remain on death row, understand that everyone is going to die. Statistically speaking, we have a much easier death than most. So I encourage you to embrace it and celebrate our true liberation before society figures it out and condemns us to life without parole and we too will die a lingering death."

Authorities said Zink abducted Morton in 2001 after hitting her car from behind on a highway exit ramp a mile (1.6 kilometres) from her Strafford home. Morton was driving home after visiting a friend.

Just months before the slaying, Zink had been released from a Texas prison after serving 20 years on rape, abduction and escape charges. Fearing that his drunken fender-bender with Morton could violate his parole and send him back to prison, Zink abducted Morton, taking her to a motel.

"If I think that you're going to pose a threat to my freedom, it is set in my mind I want to eliminate you," Zink said in his videotaped confession.

The motel's manager later saw a televised news report about Morton's disappearance, recognized her as the woman who had checked in with Zink, and gave investigators Zink's name and license plate number from motel registration.

Zink, after being arrested at his parents' home, led authorities to Morton's buried body in a cemetery, confessing matter-of-factly and at times laughing on videotape that he had tied her to a tree there and told her to look up. When the bewildered Morton begrudgingly glanced skyward, Zink said, he snapped her neck, choked her with his hands and a rope, and stuffed her mouth with mud and leaves.

Worried that Morton might regain consciousness, Zink admitted, he used a knife to sever her spinal cord at the neck.

An autopsy showed Morton had eight broken ribs and 50 to 100 blunt-force injuries. She also had been sexually assaulted.

Zink had appealed to stop his execution. A three-judge panel of the 8th U.S. Circuit Court of Appeals on Tuesday declined, without comment, his claims that the death penalty was unconstitutional. On Monday, the St. Louis-based court had rejected his challenge of the drug process used during lethal injections.

His appellate attorneys did not accept requests by The Associated Press for interviews this week.

Messages left Monday with Morton's mother and sister were not returned.

Zink became the fifth man executed this year in Missouri and the 17th since November 2013. Only Texas has executed more inmates over that span.

News from © The Associated Press, 2015