Barring intervention from the U.S. Supreme Court or the governor, Virginia planned to go ahead Tuesday with its first execution in nearly two years.

Kevin Green, 31, convicted of killing a convenience store owner in 1998, would be the third U.S. inmate to die since the Supreme Court upheld the constitutionality of lethal injection in April. Georgia became the first to execute an inmate May 6, ending a seven-month halt on capital punishment nationwide.

Green's attorneys have asked the U.S. Supreme Court to stop the execution while it considers whether to review the case. They say an appeals court erred when it ruled in February that Green had passed the statute of limitations for claiming ineffective counsel.

Attorneys for Green also have asked Gov. Timothy M. Kaine to grant clemency, claiming Green is mentally disabled.

If that doesn't happen, Green will be put to death by lethal injection at 9 p.m. Tuesday at Greensville Correctional Center in Jarratt.

Green shot Vaughan and her husband, Lawrence, while robbing their convenience store in rural Dolphin, more than 50 miles south of Richmond. Patricia Vaughan, 53, died at the scene. Lawrence Vaughan was shot but survived.

Police say Green confessed, telling them he and his nephew took a bus to northern Virginia and blew all but $170 of the $9,000 they stole on prostitutes, marijuana and clothes.

His nephew, 16 at the time, pleaded guilty and was sentenced to 23 years in prison.

Kevin Green went to trial and was found guilty of robbery and capital murder and sentenced to death in 2000. A year later, the Virginia Supreme Court ordered a new trial because of juror problems. Green was convicted again in 2001 and again sentenced to death.

The Vaughan family has waited 10 years to see the sentence carried out.

"I feel like we're the puppets and they're being the puppeteers," said Marsha Brown, one of the Vaughans' two daughters. She plans to watch Green's execution with her father, sister, husband, stepmother and two local officials.

"It's just a fine line between being hopeful and helpless. I really regret that another life has to be involved — that an execution has to happen — but I just think it needs to be carried out," she said.

Kaine, a Roman Catholic, has acknowledged an objection to the death penalty, but pledged when he was elected in 2005 to carry out the state's laws.

A federal magistrate judge decided after a 2006 hearing that Green's IQ was below the mental retardation threshold of 70 but that he could perform basic functions, such as getting a job and a driver's license.

Attorneys for Green and organizations that represent people with mental disabilities argue that the judge erred because he focused on the things Green could do instead of the real-world limitations he faced, such as language deficiencies, the inability to write and to care for himself, and difficulty with simple tasks like tying his shoes or making Kool-Aid.

They claim Virginia would become the first state to execute a mentally disabled person since the U.S. Supreme Court outlawed it in 2002 in another Virginia case.

Kaine, however, said Tuesday on a monthly call-in radio show that the courts have found Green is not mentally disabled.

Green, through his attorneys, declined to be interviewed.

He would be the 99th person executed in Virginia since the U.S. Supreme Court reinstated capital punishment in 1976. Virginia ranks second only to Texas, which has executed 405.