In Australia, He Was a ‘Great Father.’ Secretly, He Was an Escaped Convict.

A grave marker at Tamborine Mountain Cemetery in Queensland, Australia, bears the name John Vincent Damon.

For years, until he died on Aug. 6, 2010, at 69, that’s how he was known to others, including his family.

But his real name was William Leslie Arnold, and he had a secret, dark past that was unbeknown to his wife and two adult children in Australia and three surviving stepdaughters from a previous marriage in the United States.

When he was 16 and living in Nebraska in the 1950s, he fatally shot his parents during what was later described as a fight over the use of the family car and then buried them in the backyard of their home. It took about two weeks before the crime was discovered, the authorities said.

Mr. Arnold pleaded guilty in 1959 to murdering his parents, and he was sentenced to life in the Nebraska State Penitentiary. In his time there, Mr. Arnold was described by the authorities as a “model prisoner,” but on July 14, 1967, he and another inmate escaped.

The other inmate was soon recaptured. But the authorities couldn’t find Mr. Arnold for years, and the case eventually went cold. Over the past couple of years, however, investigators with the United States Marshal Service were able to gather evidence that eventually led them to crack the case through DNA testing.

The discovery came as a shock to his surviving family members, who the authorities said were completely oblivious to Mr. Arnold’s past. To them, he was John Damon, a father and husband. To the American authorities, he was a convicted killer and escaped inmate.

Surviving family members in Australia and stepdaughters of Mr. Arnold in the United States declined to comment.

Matt Westover, the U.S. Marshal deputy who cracked the case, said in an interview that connecting Mr. Arnold to John Damon was a process that spanned several years and involved sifting through thousands of pages of documents and investigating several leads across the United States as well as in Brazil and Canada.

Several law enforcement agencies over the years had tried to piece together what had happened to Mr. Arnold after he escaped. The F.B.I. investigated the case into the 1990s. Then it was turned over to the Nebraska Department of Correctional Services. Ultimately, it was passed on to the U.S. Marshals and assigned to Mr. Westover in August 2020.

“I was obsessed with the case,” Mr. Westover said.

Soon after being assigned to the case, Mr. Westover reached out to Geoff Britton, who had worked on the case from 2004 to 2013 when he was with the Nebraska Department of Correctional Services.

Mr. Britton, who is now chief of the Office of Law Enforcement Support in California, said that even after he left Nebraska, he continued to look into the case “as a hobby.” Chief Britton said that he and Mr. Westover talked frequently about it over the past few years.

“I spent a lot of nights just reading because I was just amazed at all the different information and just trying to find something, some kind of lead,” Mr. Westover said.

There were plenty of false leads.

One theory about Mr. Arnold’s whereabouts was that he had fled to Brazil. That was based on an immigration document with Mr. Arnold’s name on it issued to someone in Brazil less than two years after the prison escape. But Mr. Westover said Brazilian officials didn’t have any record of Mr. Arnold, and it was unclear why his name was on that document.

Mr. Westover tracked down an ex-girlfriend of Mr. Arnold, which led to a trove of letters that he had written to her and her family from prison. But there was no correspondence from after his escape that provided any clues as to where he had ended up.

Mr. Westover also found a postcard from Canada and one from California with Mr. Arnold’s name. Those leads were also fruitless.

In a wanted poster for Mr. Arnold, the U.S. Marshals Service said that he was “very musically talented and most likely used these skills to financially survive.” That detail of his life also did not yield any leads.

“It just seemed like everything was working against us,” Mr. Westover said.

Over time, various leads led investigators to determine that after Mr. Arnold escaped prison, he had fled to Chicago, where he started going by his new name, John Damon, and quickly met and married a woman with children. He then began to move around, living in Cincinnati and Miami, according to The Omaha World-Herald, which has chronicled Mr. Arnold’s life through a series of articles and a podcast. Later, he divorced his wife and moved to California, where he remarried and had children, and eventually settled down in Australia.

Finally, in November 2020, Mr. Westover tracked down a brother of Mr. Arnold in Missouri, who agreed to provide a DNA sample. Later, in August 2022, Mr. Westover connected with a man from Australia who was trying to learn about his late father, John Damon, who had told him that he was an orphan from Chicago.

DNA samples from Mr. Arnold’s brother and Mr. Damon’s son indicated a match, and proved that Mr. Damon was really Mr. Arnold.

“It was thrilling,” Mr. Westover said. “I won’t say it’s like hitting the lottery because I’ve never hit the lottery — I’m sure that’s a pretty good feeling — but I was just ecstatic.”

Then came the hard part: Mr. Westover had to break the news to the man from Australia that the father he knew as John Damon was actually an escaped convict who had killed his parents. Mr. Westover said he had told the man over a video call.

“That was a really hard conversation to have,” Mr. Westover said. “Their family didn’t know any of this stuff, and so it’s hard not to feel bad for them.”

Chief Britton said that he has since spoken to Mr. Arnold’s family in Australia, trying to help answer questions about his history that they knew nothing about.

“They’re getting a new perspective on a man that they had a completely different view of,” Chief Britton said. “That’s got to be hard to process.”

In getting to know the Damon family, Mr. Westover said that he learned that Mr. Arnold had gone on to become a businessman in Australia, and ended up living a “great life and apparently changed his ways.”

“He was a great father to them,” Mr. Westover said.

In March, Mr. Westover and other investigators traveled to Australia to wrap up the case. While they were there, they visited the grave of John Vincent Damon.

“I’m glad he’s dead,” Mr. Westover said, explaining that if Mr. Arnold were still alive, he would be facing arrest in his 80s.

“As bad as that sounds, I’m glad because I really wouldn’t want to put their family through that,” Mr. Westover said. “I think they had been through enough already, let alone if I was to take their dad from them.”

Kirsten Noyes contributed research.