EVER SINCE taking office four years ago, Virginia Gov. Mark R. Warner (D) has faced the question of whether to revisit the case of Roger Keith Coleman, who was executed in 1992. Both before and since Mr. Coleman was put to death, the question of his guilt has haunted Virginia's justice system. An early generation of DNA testing suggested that he did rape and murder his sister-in-law, Wanda McCoy. But the test's methodology has always been controversial, and physical evidence remains that might yield more conclusive results. Testing it should never have been a tough call.

Yet Mr. Warner has dithered -- and dithered some more. When a New Jersey charity that investigates wrongful convictions petitioned him for the testing, he sat on the request. When Mr. Coleman's prosecutors declared that they had no objection to the testing, he did nothing. He said on more than one occasion that he was wrestling with the question. Now he is about to leave office, and he declared last week that before he goes, he will decide whether to pursue the testing. His office has recently taken steps to reach an understanding concerning how the testing would take place both with the charity and with the scientist who has been the custodian of the evidence since conducting the earlier tests. But he still has not decided whether to go forward. If Mr. Warner leaves office without ordering the testing, it will represent a failure of nerve that should be remembered if and when he tries to present himself as a decisive leader in a presidential contest.

It would take little political courage for Mr. Warner to order the testing. He played no role in Mr. Coleman's conviction or execution. What's at stake is the principle that in the face of uncertainty the state has an obligation to learn and report the truth, however uncomfortable that may be. You'd think the governor also would want to learn whether a murderer remains at large. Testing might wipe away a doubt that has stained Virginia's criminal justice system for more than a decade, or it could show that the system failed. Mr. Warner has said he worries about a third possibility: that testing would yield no conclusive result. But that would leave public understanding of the case largely unchanged, since the evidence now is hardly conclusive.

Mr. Warner's other concern, expressed in the past, is with upsetting the finality of a verdict. But the finality of a wrong verdict is not worth protecting. If Mr. Coleman was innocent, refusing to find that out means perpetuating an already irremediable injustice -- and forgoing the prosecution of whoever killed Ms. McCoy.