In opening a review of the former territorial governor's deal to grant clemency to Billy the Kid, Mr. Richardson has revived the classic Old West showdown between the Kid and the sheriff who arrested him — and later shot him — nearly 130 years ago.

The governor sat down with three of Sheriff Pat Garrett's grandchildren and two great-grandchildren in his office recently and listened to what he described as their “heated” defense of their ancestor.

“This is our history, and it's important to New Mexico and we can't arbitrarily alter it,” said Susannah Garrett, 55, a granddaughter of the sheriff.

Historical documents show that Mr. Wallace struck a deal with the Kid that if he would testify before a grand jury about a killing he had witnessed, the governor would grant him a pardon for his many crimes. Billy the Kid did testify but the pardon never came, something the outlaw grumbled about as he managed to escape the law, get caught and then escape again, only to be gunned down in the dark by the frontier lawman in 1881.

Pardons are granted by governors across the country, especially departing chief executives like Mr. Richardson, who has served eight years in office and is prevented by term limits from running again.

But the proposed clemency for Billy the Kid, who also went by the names Henry McCarty and William H. Bonney, is provoking strong reactions in this history-minded state — even more so because people who claim family links to the central characters in the drama still live here.

“There's still family involved,” said Dorothy Massey, who co-owns the Collected Works Bookstore, which was recently found to be on the site of an old jail in Santa Fe where the Kid was briefly detained. “If Pat Garrett had no kith and kin and Billy the Kid had no kith and kin, this would be history and nothing more.”

At Ms. Massey's bookstore recently, two members of the Garrett family sipped coffee with descendants of John Henry Tunstall, a rancher who once hired Billy the Kid and whose murder in 1878 set off the Lincoln County War.

Elbert Garcia of Santa Rosa, N.M., a retired aerospace executive in his 70s who professes to be a great-grandson of the Kid, has pushed for a pardon for his relative when the issue has come up in the past but has stayed quiet this time around.

When a New Mexico lawmaker proposed a pardon for Billy the Kid in 2001, the main opposition came from the offspring of Sheriff William Brady, who was ambushed and killed in southern New Mexico in 1878 by a group of outlaws that included the Kid.

This time around, Garrett descendants, fearful that their ancestor's reputation is being besmirched, are waging a public campaign to urge the governor to abandon the pardon and back the sheriff. They were particularly upset by an investigation that Mr. Richardson initially supported into whether their ancestor shot the wrong man.

“If Billy the Kid were living amongst us now, would you issue a pardon for someone who made his living as a thief and, more egregiously, who killed four law enforcement officers and numerous others?” the Garrett family wrote to Mr. Richardson last month.

But no modern-day cop killer has the romanticism attached to him that Billy the Kid does. Despite the strong objections by some, the governor is holding out the possibility of an 11th-hour pardon, which he acknowledges would be rooted both in history and publicity. (New Mexico's official tourism Web site is heavy on Billy the Kid lore.)

“It will be based on the facts, on the documents, on the discussions between Lew Wallace and Billy the Kid,” Mr. Richardson said in his office this week. “It's a question of whether as a governor, I would be fulfilling my obligations in the area of pardons by fulfilling this promise that was never kept.”

He added, “Admittedly, this also gets good publicity for the state.”

The governor's critics say it also draws more attention to Mr. Richardson, whose presidential ambitions were quashed and who had to withdraw from consideration for a post in the Obama administration because of a conflict-of-interest investigation that has since been closed. As for his future plans, Mr. Richardson said, “I'm going to fade into the sunset like Billy the Kid.”

Then he quipped, “Hopefully, I won't have the same outcome.”

New Mexico leaves pardons solely up to the governor's discretion — “unrestrained by any consideration other than his conscience, wisdom and sense of public duty,” the state's executive clemency guidelines say.

Whether a Billy the Kid pardon makes good sense is being hotly debated here by Kid experts, who seem to be a wide-ranging group that includes bona fide historians and men on sidewalks strumming guitars for tips. Mr. Richardson says his mail shows the state about evenly split on the issue.

The state's historian, Rick Hendricks, is on the no side, although he said Mr. Richardson had not yet asked him his opinion.

“The governor may have developed some information that I'm not privy to,” Mr. Hendricks said. “Barring finding any new documentation that gives me more information into the thought process of Governor Wallace, I would be hard pressed to make that determination.”

Bob Ross, the amateur Billy the Kid historian who managed to document last year that the jail that held the Kid was a block from where a plaque said it was in downtown Santa Fe, also came down against a pardon.

“It's a vain gesture at this point,” Mr. Ross said. “The purpose of pardoning him would be to save his life. It's too late for that. By pardoning him, what are you saying? Are you saying he didn't kill Sheriff Brady? The facts are hard that he did and that he was a professional horse and cattle rustler.”

But Mark Lee Gardner, author of “To Hell on a Fast Horse: Billy the Kid, Pat Garrett and the Epic Chase to Justice in the Old West,” said that the Kid was offered a deal by Mr. Wallace and that it should be honored, even all these years later.

The debate, though, Mr. Gardner considers a good thing.

“In an age when we don't think people are passionate about history, this is refreshing,” he said. “Everyone is talking about this.”

The Kid's fame as a gun-slinging outlaw grew from his exploits during the Lincoln County War, a feud that bathed central New Mexico in blood. Mr. Richardson said that if he did decide to go ahead with a pardon, he would first air the issue at a big public gathering in Lincoln County. The only warring that would be allowed would be with words.