11/08/2012 01:36 pm ET

Bill Macumber, Imprisoned For 1962 Arizona Double Murder, Pleads No Contest And Walks Free

After nearly four decades behind bars, an Arizona inmate who long maintained that his ex-wife framed him for a double-murder walked out of prison a free man.

Bill Macumber, 77, received a sentence of time served when he pleaded no contest to two counts of second-degree murder on Wednesday, allowing his release under an agreement with prosecutors in Maricopa County Superior Court, the Arizona Republic reports.

Macumber was twice convicted of the 1962 slayings of Joyce Sterrenberg and Tim McKillop, two telephone company workers and had been serving a life sentence, the Associated Press reports.

Though Macumber is a free man, Judge Bruce Cohen still cast doubt on his innocence.

“We will never know with certainty what happened on that 1962 night,” the judge said in court.

According to ABC News:

On May 24, 1962, the young couple was found shot and killed next to their car in an area now near Scottsdale. The case went cold for 12 years until Macumber's wife, Carol Kempfert, went into the Maricopa County Sheriff's Office department where she worked and told her supervisors that her husband had confessed to the murders. Macumber was arrested a week later.

With Kempfort's testimony, County prosecutors built a case against Macumber using a palm print, .45 handgun, and bullet casings found at the crime scene.

After the state Supreme Court overturned the guilty verdict in his initial trial, a second ruling convicted Macumber.

Macumber insisted he was innocent and eventually the Arizona Justice Project picked up the case. The organization, which works to free wrongly convicted prisoners, filed a motion calling into question the ballistics and handprint evidence as well as the testimony of Macumber's ex-wife.

They also presented previously ignored evidence -- a confession from a man named Ernest Valenzuela. In 1964, Valenzuala admitted to authorities that he killed two people in the desert near Scottsdale. By the time Macumber went to trial, however, Valenzuala had already died in a prison fight.

In 2009, Gov. Jan Brewer denied a recommendation from the state's clemency board suggesting Macumber's life sentence be reduced.

Asked by ABC News if she framed her ex-husband, Kempfort responded, "No, absolutely not."

A cousin of one victim was upset with the decision to release Macumber.

"How do you take a blow in your stomach? How do you describe that? We know he's guilty," said John McCluskey, according to CBS-5. "We know in our hearts that man killed those two young people."