Roger Keith Coleman's last words -- "an innocent man is going to be murdered tonight" -- will finally be put to a test.

In a decision that could influence how capital punishment is administered in Virginia, Gov. Mark Warner announced Thursday he has ordered DNA tests to determine whether Coleman was executed more than a decade ago for a crime he did not commit.

"This is an extraordinarily unique circumstance, where technology has advanced significantly and can be applied in the case of someone who consistently maintained his innocence until execution," Warner said.

"I believe we must always follow the available facts to a more complete picture of guilt or innocence."

Should the tests show Coleman was innocent -- a prospect many people familiar with his case say is unlikely -- it would mark the first time in the United States that scientific evidence has shown that an innocent person was executed, according to the Death Penalty Information Center.

"Either way the tests go, it will be a very significant event in the national debate over the death penalty," said Paul Enzinna, a Washington, D.C., attorney who asked Warner nearly three years ago to order the tests.

Enzinna represents Centurion Ministries, a New Jersey group that investigated Coleman's case and believes he did not rape and murder his sister-in-law in 1981.

Coleman was put to death for the crime in 1992, maintaining his innocence in his final words from the electric chair.

A possible answer to the questions that have lingered ever since has remained in the California laboratory of Edward Blake, a forensic scientist who preserved a piece of crime scene evidence that Warner now wants tested.

At issue is a semen sample taken from the body of Wanda McCoy, who was found dead in her Buchanan County home in far Southwest Virginia. She had been raped and her throat was slashed.

Because DNA testing did not exist at the time of Coleman's trial in 1982, authorities could only use blood typing to narrow the pool of suspects to include Coleman.

Post-trial testing of the sample made the pool smaller. At the request of Coleman's appeal lawyers, DNA tests were conducted in 1990 by Blake, the California scientist who held on to the remaining sample.

Blake's tests put Coleman within 2 percent of the population that could have produced the sample. According to the state, additional analysis reduced the range to just 0.02 percent.

Now that more advanced testing can remove all doubts -- assuming the frozen sample has not deteriorated too much with age -- the remaining evidence will be tested by Ontario's Centre of Forensic Sciences lab in Toronto. Testing has already begun on one portion of the evidence, according to Warner's statement, and a second round is about to begin.

Warner said he hopes the results will be available before his term ends Jan. 14.

"This is an example of justice triumphing over politics," said Jack Payden-Travers of Virginians for Alternatives to the Death Penalty. Payden-Travers had expressed concerns earlier that Warner would stonewall the request to avoid political fallout.

"Justice demands, and families deserve, certainty in these cases," Payden-Travers said. "We need to know if the person punished for a crime actually committed the crime."

If Coleman is found to have been innocent, opponents of the death penalty are sure to use his case to advance their cause. An immediate effect could be seen in the General Assembly, which once again will consider a bill this year to impose a moratorium on executions.

In the past, lawmakers have balked at such proposals, saying they have seen no evidence that the ultimate punishment was exacted in error. "We've had legislators who have said: 'Show me a body, and I'll introduce a bill.' "

Should Coleman be exonerated posthumously, Payden-Travers said his response will be: "Here's the body. Where's your bill?"

And if the tests go the other way, he said, at least there will be a final resolution to the questions in Coleman's case -- and a precedent set by Warner that Virginia should not use an execution as the death knell to entertaining similar questions in other cases.