Authorities had been searching for John McCluskey and his fiancée, Casslyn Welch. (Mohave County Sheriff's Office)

A U.S. prison escapee and his fiancée who had been on the run since July 30 have been captured, police say.

John Charles McCluskey, 45, and Casslyn Welch, 44, were arrested Thursday in Apache County in northeastern Arizona, according to reports.

Sgt. Richard Guinn of the Apache County Sheriff's Office told The Associated Press that a team of officers arrested McCluskey and Welch on Thursday evening after Forest Service employees spotted the pair and reported them to authorities. Guinn said McCluskey turned when confronted by officers but was immediately put on the ground.

Authorities had been searching for the two since McCluskey escaped from the medium-security Arizona State Prison on July 30 with two other inmates. Police suspect Welch was an accomplice in McCluskey's escape.

The two other inmates were subsequently caught in Wyoming and Colorado.

Earlier this month, Welch was apparently spotted 2,500 kilometres away at a Montana restaurant on the edge of Glacier National Park, just south of the border with Alberta.

Major search

That prompted a major search by U.S. marshals in the northern state and led Interpol to issue an international alert for the couple.

The Canadian Border Services Agency had put its officers on alert for the pair in case they were thinking of crossing into Canada.

The RCMP in Alberta had also moved a helicopter to Lethbridge to be closer to the U.S. border.

Forensic evidence has linked the escapees with the killings of a couple in New Mexico whose bodies were found in the charred wreckage of a camper a week ago.

McCluskey had been serving a 15-year sentence for attempted murder.