Criminal justice was not high on Mark Warner's to-do list when he was elected governor of Virginia in 2001. And he did not mention the subject in his farewell address to the Legislature on Wednesday.

But in four years as governor, Warner has incrementally and with little fanfare established groundbreaking policies on the use of DNA testing to confirm, or challenge, criminal convictions, many of them in death penalty cases. Last week, he became the first governor to order a DNA test involving a man who had already been executed.

The actions of Warner, who leaves office today, have established new middle ground in the polarized world of death penalty politics. Unlike former Gov. George Ryan of Illinois, who ordered a moratorium on executions in 2003, Warner has not called for halting executions, and he still supports capital punishment. His goal, he has said, has not been to undermine the system but to make sure it works.

"It's not like he wants to be a DNA or criminal justice crusader," said Ellen Qualls, Warner's spokeswoman. "It is not his hope that his actions will help the death penalty abolition movement. In each case, he's just tried to pick the right course."

But because Warner, a Democrat, is considering a run for president in 2008, his actions are being scrutinized for political motives.

"He's heading for Iowa," said Michael Paranzino, president of Throw Away the Key, a nonprofit group that supports the death penalty. Paranzino was referring to the Iowa caucuses that kick off the presidential campaign season.

Warner's supporters strongly dispute that. They argue that any gains he makes during the primaries from questioning capital punishment would become setbacks in the general election, when Republicans might attack him as soft on crime.

Regardless of motives, Warner has gone further than other governors in using newer, more sophisticated DNA tests to review prosecutions, experts said. In the last two years, he ordered two sweeping reviews of DNA testing and other forensic analyses by the state's crime laboratory.

"He has set an example for governors all over the United States," said Peter Neufeld, co-director of the Innocence Project, a legal clinic based in New York. "It's the governors' responsibilities to go out and do DNA testing in these cases. That is the only way you can enhance the integrity of the criminal justice system."