Carol Kempfert also sat down for an interview with "Nightline" in 2010, where she denied she fabricated her husband's confession.
"Absolutely not ... I didn't wake up one more morning and say, 'Oh, gee, I think I'll go frame my husband today,'" she said at the time. "I did not, and I will say this again, I did not manufacture nor did I ever tamper with evidence. Ever. And I passed four polygraphs and I'll be happy to take another. But I did not tamper with any evidence."
Kempfert told of how Macumber came home with his clothes covered in blood the night of the murders, and that he later confessed to her as their marriage crumbled.
"It sounds ... ridiculous. But that's, in fact, what happened," she said.
But adding fuel to Ron's belief that his father is innocent, a man named Ernsesto Valenzuela allegedly confessed to three different people that he had committed the murders -- evidence the jury at Macumber's trial never was able to hear.
After Valenzuela died in prison in 1973, his former defense attorney, Tom O'Toole, came forward with his client's confession but the judge ruled it unreliable hearsay, reported The New York Times. O'Toole said attorney-client privilege kept him from presenting Valenzuela's confession until after his death.
"I believe [Valenzuela] told me about committing those murders because he got pleasure in committing those kinds of crimes and he relished it," O'Toole said. "He analogized shooting one of those people to it being like shooting a rabbit... he was thriving on it, he loved it."
In 2009, Macumber and his attorneys petitioned the Arizona Board of Executive Clemency, which in a rare move unanimously recommended his sentence be commuted, saying, "An injustice has been done in Mr. Macumber's case" and that his wife had "motive, means and opportunity to falsely pin the murders on Mr. Macumber."
Arizona Gov. Jan Brewer denied the recommendation for clemency.
In 2011, Macumber petitioned the Court for post-conviction relief and was granted an evidentiary hearing. But without the necessary evidence, prosecutors said in court today they were unable to retry the case for a third time. Now that the judge has accepted Macumber's plea, he will be released.