DENVER — Two Afghan prison officials who walked away from a prison-reform training program in Colorado pose no threat, and their names are being withheld for fear their families back home will be retaliated against by those opposed to U.S. involvement there, officials said.

Their disappearances underscore a difficulty American officials face in training civilian and military Afghan nationals in the United States, then sending them home, where they can face reprisals from the Taliban or other elements hostile to the U.S.-backed government.

One Afghan official left a training center in Canon City in southern Colorado in September 2013. The other disappeared in February. One of the men was found while trying to enter Canada, the Denver Post reported Monday.

The other man has not been located.

The reasons the men left were unknown. State and federal officials opted against releasing their identities out of concern for the men’s well-being and the safety of their families in Afghanistan, said Adrienne Jacobsen, spokeswoman for the Colorado Department of Corrections.

Both passed U.S. State Department background checks before joining the training program, Jacobsen said.

“There is absolutely no reason to believe they would be involved in any terrorist activity or any wrongdoing at all,” she emphasized.

In Massachusetts, three Afghan soldiers abandoned a U.S. training exercise in September to avoid returning to Afghanistan. They are seeking asylum. The soldiers were detained at the Canadian border, and they face deportation for allegedly overstaying their visas.

The soldiers have said they were seeking protection against Taliban death threats at home. They now also fear reprisals from Afghanistan authorities if they are made to return.

In the Colorado case, Republican gubernatorial candidate Bob Beauprez sought to capitalize on the disappearances. Beauprez’s campaign, which has made crime issues under Democratic Gov. John Hickenlooper a central theme, issued a statement suggesting the men posed a danger to Coloradans.

“John Hickenlooper’s Department of Corrections said that their main concern was for the safety and privacy of the runaway Afghans; I think their first concern should be for the safety of the people of Colorado,” Beauprez’s statement said.

Hickenlooper previously criticized Beauprez for a campaign television ad that used the 2013 slaying of Colorado corrections director Tom Clements by a former inmate. Clements’ widow asked Beauprez to stop referencing her husband’s death. Beauprez ultimately did so.