By many accounts, Chris Thomas and his girlfriend were both in on the killing of her parents. But when it came time for justice, Thomas received the death sentence while his girlfriend, Jessica Wiseman, became a free woman.

In one sense, Thomas's supporters say, he was the victim of bad timing. Although both of the accused were juveniles--Thomas was 17 and Wiseman was 14--only Thomas was tried as an adult.

He is scheduled to die Wednesday night unless Gov. James S. Gilmore III (R) accepts pleas to halt the execution based on questions about whether Thomas killed both of Wiseman's parents and about the disparity in punishment.

At the time of the crime in 1990, no one under 15 could be tried as an adult in Virginia, no matter how heinous the crime. Wiseman got a closed hearing in Juvenile Court, which found her to be a delinquent and ordered her confined in a juvenile facility until her 21st birthday, which was July 26, 1997. On that date, she was freed.

As for Thomas, Virginia juries did not have the choice of sentencing a killer to life in prison without the possibility of parole. So the choice came down to execution or prison time that could be as little as 20 to 25 years. Thomas was sentenced to death.

Since the murders, Virginia has changed its laws in ways that might have affected the outcome of both cases. As of July 1, 1994, juveniles as young as 14 could be charged as adults. On Jan. 1, 1996, the state abolished parole.

On Nov. 10, 1990, James B. and Kathy Wiseman, both 32, were shot in their Middlesex County home, which they shared with their daughter. Prosecutors said the couple objected to their daughter's relationship with Thomas. The boy, they said, went into the parents' bedroom and shot each of them once while they slept, but Kathy Wiseman managed to run to her daughter's bedroom, where she was shot again.

Thomas pleaded guilty to first-degree murder in the shooting of James B. Wiseman and not guilty to killing Kathy Wiseman. A jury found him guilty of that killing, too.

Under Virginia law, a death sentence can be meted out only in certain circumstances, which must include a first-degree murder and another offense, such as murder during a rape or robbery, or a multiple murder. Even then, the jury must find that the murder was particularly vile, or that the murderer showed signs of being a danger in the future.

Attorneys for Thomas say that both before and after the trial, he told Jessica Wiseman that he was willing to protect her by taking the blame for both killings.

Thomas's lawyers want to talk to Wiseman but cannot find her.

This week, two Richmond women who spent time in jail with Wiseman came forward to say that she had told them it was she, not Thomas, who fired the shot that killed her mother.

In an affidavit submitted to Gilmore along with a petition for clemency, a woman identified publicly only as Nicole said that in 1990, she and Wiseman were held at the Richmond Juvenile Detention Center and that during their stay, Wiseman told her and others that "Chris killed my father, and I killed my mother."

Nicole, who was in the juvenile lockup for fighting in school, added that Wiseman said she that had been "abused all my life" by her parents and that "Chris wanted to run away; he didn't want to do this. But I wanted to make my parents feel the pain that they had caused me."

This afternoon, another woman, identified as "J," said she was Wiseman's roommate at the Bon Air Correctional Center, where Wiseman spent most of her sentence.

"J," who said she provided Gilmore with her full identity, said Wiseman told her that her wounded mother came to her room asking, "Why, Jessica, why?" and that her daughter then shot her.

If that is true, Thomas's crime would not have qualified for the death penalty, according to Rob Lee, director of the Virginia Capital Representation Resource Center.

But David Botkins, spokesman for Virginia Attorney General Mark L. Earley (R), disagreed, saying Thomas "is guilty of murder--regardless. . . . Even if Thomas's girlfriend . . . was involved, it doesn't exonerate him. . . . The brutal murders were cold and calculated."

Gilmore's deputy press secretary, Lila Young, said today that "the governor will review the entire case, including the affidavits, and if his lawyers want to meet again, we will be glad to do that."

The U.S. Supreme Court, by a vote of 7 to 2, with Justices Ruth Bader Ginsberg and John Paul Stevens dissenting, rejected an appeal from Thomas on Monday.

If the execution goes forward, Thomas, now 26, would be the second juvenile offender executed in Virginia since 1924. Last October, Duane Allen Wright, 26, of the District, was executed for killing an Annandale woman and two others in a five-day shooting spree in 1989, when he was 17.

Nationally, of the 3,600 inmates on death row, only 74--about 2 percent--were under age 18 at the time of their crimes, according to Richard Dieter, executive director of the Death Penalty Information Center.

CAPTION: Chris Thomas, left, and Jessica Wiseman, above, leave courthouses in Virginia after court proceedings in 1991 in the killings of her parents.