(Adds Ferguson's final statement, family statement)
By Carey Gillam
BONNE TERRE, Mo., March 26 (Reuters) - Missouri officials executed a man early on Wednesday who was convicted of abducting a teenage girl at the gas station where she worked, then raping and strangling her.
Jeffrey Ferguson, 59, was pronounced dead at 12:11 a.m local time (0511 GMT) at a state prison in Bonne Terre, said Mike O'Connell, a spokesman for the Missouri Department of Public Safety. He was the third man executed in Missouri this year.
Ferguson was twice convicted of killing 17-year-old Kelli Hall, whom he kidnapped with an accomplice as she ended her evening shift at a metropolitan St. Louis service station on Feb. 9, 1989. The girl's naked body was found less than two weeks later.
Ferguson was given a lethal injection of 5 grams of pentobarbital, a fast-acting barbiturate at 12:01 a.m. local time, O'Connell said.
Ferguson, covered neck to toe with a white sheet and strapped to a gurney, mouthed words and seemed to smile as a group of friends and family blew him kisses just as the drugs began to flow, said a Reuters reporter at the prison.
His legs made a flurry of kicking motions under the sheet but he quickly appeared to slip into unconsciousness and took only a few shallow breaths before becoming still. Two young women in the family witness room began to cry.
"She was 17 years old. She had her life in front of her," Jim Hall, Kelli's father, told reporters after the execution as he choked back tears. "It's been a very long 25 years waiting for this execution. Hopefully we can now move forward."
Ferguson's first conviction in 1992 was overturned due to a problem with the jury instructions. He was convicted in a second trial and again sentenced to death.
The U.S. Supreme Court late on Tuesday denied last-minute petitions seeking to stay the execution.
Attorneys for Ferguson had filed several appeals to try to delay or halt his execution, arguing, among other things, that an FBI agent gave false and misleading testimony at his trial.
Missouri Governor Jay Nixon on Tuesday denied a clemency petition for Ferguson, finding the jury's decision appropriate.
According to prosecutors, Ferguson had been out drinking at a bar with a friend and then went to meet another friend at the gas station where Hall was ending her shift. Hall was checking the fuel levels in the station tanks when a witness saw her being forced into the back seat of a vehicle by a white male.
The next day a maintenance worker found Hall's coat and clothes discarded at the side of the road. A farmer later found her battered and frozen body hidden in a machinery shed.
Ferguson requested and was given an oral sedative early in the evening, prison officials said. For a final meal he ate barbecue ribs, French fries and apple pie. Before being put to death, Ferguson stuck his tongue out and wiggled it toward his relatives.
"At this point in my life, I believe that I am the best man that I've ever been," Ferguson said in a final statement. "I'm sorry to have to be the cause that brings you all into this dark business of execution."
Ferguson's execution comes at a time when Missouri, and several U.S. states, are under fire for turning to lightly regulated compounding pharmacies for their lethal injection drugs.
Major pharmaceutical companies have stopped allowing sales of their drugs for executions, leaving U.S. states scrambling to come up with alternatives.
Two executions planned for March in Oklahoma were postponed until April after the state said it was having trouble obtaining the drugs it needs to perform executions.
Advocates for inmates say drugs from compounding pharmacies can lack purity and potency and cause undue suffering in violation of the U.S. Constitution's protections against cruel and unusual punishment.
Ferguson is one of a group of Missouri inmates who sued state officials in 2012 in a challenge to the constitutionality of the state's execution protocols. The case is set for trial on Sept. 15.
Missouri has since made a series of changes to its execution protocols. The state is now under scrutiny for adding layers of secrecy to its practices, including its efforts to source drugs from compounding pharmacies. The state has also been criticized for carrying out executions while appeals are awaiting court review. (Reporting by Carey Gillam in Bonne Terre, Mo. and Eric M. Johnson in Seattle; Editing by Ken Wills and Andrew Heavens)