US spy Mike Beck felt his body start to deaden. Then he found out his partner's body had too.

One of the first signs came at the keyboard.

Mike Beck, a US National Security Agency counterintelligence officer, could always bang out 60 words a minute. But in early 2006, Beck struggled to move his fingers at their usual typing speed.

He had to hunt and peck.

KATHERINE FREY/THE WASHINGTON POST Mike Beck keeps mementos from his NSA career at his home.

Soon after, a brain scan showed why: Beck had Parkinson's disease, the second-most-common neurodegenerative disorder in the United States, behind Alzheimer's.

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He was only 46 - unusually young for Parkinson's. No one in his family had ever had it. Then, in an unsettling coincidence, he learned that an NSA colleague - a man he'd spent a pivotal week in 1996 with in a hostile country - had also just been diagnosed with Parkinson's.

Eventually, Beck read a classified intelligence report that convinced him that he and his co-worker were likely the victims of a covert attack on the trip that led to their illnesses - and have led to a highly unusual workers' compensation claim.

Beck believes that while he and his colleague were sleeping in their hotel rooms, the hostile country, which he cannot name for security reasons, deployed a high-powered microwave weapon against them, damaging their nervous systems.

"I was sick in the stomach and shocked when I read that report," said Beck, who now struggles to drive, fold the laundry, clean the dishes, or get deep sleep. "I am familiar with other things this hostile country does, and it just felt raw and unfair."

For the last four years, Beck, 57, has been trying to persuade the Labour Department to award him 75 per cent of his salary, or about US$110,000 a year.

But the Labour Department won't approve Beck's request without solid evidence that he was targeted.

In Beck's case - short of obtaining proof from the hostile nation's spy service - he'd need the endorsement of the NSA, which has refused to provide it.

NO PROOF

Glenn Gerstell, the NSA's general counsel, said the agency has not found any proof that Beck or his co-worker were attacked.

Absent evidence, the NSA can't tell the Labour Department whether it agrees or disagrees with Beck's claim, he said.

"We have tremendous sympathy for him, and we'd like to try and help him. But we can't manufacture evidence," Gerstell said.

"If the Department of Labour asked us, 'Do you think this is a possibility?' then that would be different. But they didn't ask that."

A Labour Department spokesperson said the agency does not comment on active cases.

"This is not your average workers' compensation claim case, like someone falling while they were working on the roof of a government building," said Mark Zaid, Beck's attorney, who has represented spy agency employees for decades.

"How often is it that a foreign government attacks a federal employee with devastating microwaves?"

THE CUBA SYMPTOMS

Working overseas can be dangerous for US intelligence and diplomatic personnel.

The State Department said in September that it was pulling most of its staffers back from Cuba, after revelations about a series of mysterious attacks that injured 24 Americans stationed in the country.

The Americans complained about numerous symptoms, including hearing loss, dizziness, headaches, even cognitive issues.

Cuba has denied responsibility. The ordeal has led to speculation that the Americans were victims of a sonic or acoustic attack.

THE TRIP

Beck, a former Secret Service officer who joined the NSA in 1987, was accustomed to working in hostile terrain. He made sure that US facilities around the world could protect intelligence in physical spaces known as "sensitive compartmented information facilities," or SCIFs.

In 1996, Beck and his colleague, Charles Gubete, were sent to a foreign nation to assess an American facility's safeguards for classified information.

He can't say exactly where, not even which hemisphere. The NSA's presence in the country is secret, the agency told the Labour Department.

When they arrived, Beck said, a soldier detained them in a small conference room at the airport but didn't explain why, and then released them after about two hours.

Beck said he and Gubete didn't identify themselves as NSA employees.

Afterward, Beck said their translator intimated that the host country had been observing them.

The two men stayed for about a week in side-by-side hotel rooms. Beck can't divulge much about what they did, he said, "But we found something very important to the focus of our mission, something threatening near the building."

THE BRAIN SCAN SHOCK

A decade later, the right side of Beck's body began to deaden.

His right arm didn't swing normally while he walked. His right hand stiffened, so he typed with his left. Then his right leg started to drag. He felt like he was always about to slip on his office's polished stone floors.

At the time, Beck, his wife, Rita, and two children were living outside London, while he worked at the NSA's British counterpart, the Government Communications Headquarters.

The brain scan revealing young-onset Parkinson's was a shock. Only 10 to 20 per cent of those diagnosed with the illness are younger than 50.

Beck was put on standard Parkinson's medication, called dopamine agonists, that helped restore his body movement. As his three-year tour in Britain wrapped up, he was offered a fourth year, and accepted.

CONVINCED THE AILMENTS ARE LINKED

Beck was well-regarded. He'd received a personal note of thanks from then-FBI director Robert S. Mueller III for helping catch Brian Regan, a retired Air Force master sergeant who tried to hawk classified material to China, Libya and Iraq for US$13 million.

But even as the medication reduced many of his symptoms, Beck learned that Gubete, his travel partner, had also been diagnosed with Parkinson's.

He thought back to their trip in 1996 and wondered whether their ailments shared a link.

Then, in 2012, Beck and others were emailed the intelligence that convinced him there was a link.

Over lunch, he shared his suspicions with Gubete, who by then was retired and no longer held a security clearance.

So Beck couldn't tell him much about the intelligence. Gubete, who lived in Laurel, Maryland, died a year later, though the cause remains unknown. He was 61.

Parkinson's ran in Gubete's family. His mother and great-grandmother had it, according to Gubete's sister, Carol Owens, who lives in Pennsylvania.

Beck's doctor, Paul Fishman, a professor of neurology at the University of Maryland School of Medicine, said in an interview that since Gubete's relatives had Parkinson's, it is far less likely the alleged microwave attack led to his diagnosis.

And he wasn't sure it had a connection to Beck's.

Still, Fishman maintained it was possible that the microwave weapon could have helped cause both men's neurological damage.

"There are genes that raise your risk for Parkinson's, but it's not 100 per cent that people who carry those genes get Parkinson's," Fishman said. "It's well-established that two causal factors can add together."

WHAT CAUSES PARKINSON'S?

The exact cause of Parkinson's is unknown, but genetics and exposure to environmental elements - pesticides and other toxic chemicals - can increase someone's risk.

Military veterans with Parkinson's who were exposed to Agent Orange, a toxic defoliant the US deployed during the Vietnam War, may be eligible for disability benefits.

But David Standaert, chairman of the American Parkinson Disease Association's scientific advisory board, said he doesn't know of any published literature linking high-energy microwave rays and Parkinson's.

PUSHING FOR COMPENSATION

Beck began exploring a workers' compensation claim in 2012. At that point, six years into his diagnosis, Beck was getting tired much more easily and his dexterity was diminishing. He filed the claim in 2013.

As the Labour Department gathered evidence, the NSA never commented on whether it agreed with Beck's allegation that his Parkinson's was connected to his 1996 trip overseas, according to the case's records.

Beck gave the Labour Department an unclassified version of the intelligence he'd read: an NSA statement saying that the hostile country's weapon "may have the ability to weaken, intimidate, or kill an enemy over time and without leaving evidence" and that it is designed to cause "numerous physical effects, including a damaged nervous system".

Beck also submitted a paper by an NSA counterintelligence agent declaring that the attack against Beck was "highly probable."

But the NSA refused to allow Beck's attorney, Mark Zaid, to review the classified information, although Zaid holds the highest level security clearance for his cases.

"Not only did the NSA refuse to help Mike, they also obstructed my ability to help him," Zaid said.

Gerstell, the NSA general counsel, said that not even the classified information proves Beck's allegation that his Parkinson's is work-related.

In September 2014, the Labour Department rejected his claim, citing the absence of the NSA's endorsement.

Beck felt deflated. He was inching toward three decades of service at the NSA.

"I felt frustrated and confused as to why the agency didn't respond," said Beck, who is appealing the case. "There were no limitations on what the NSA could have said. They could have said it was possible."

A 'NO BRAINER' THAT THE ATTACK HAPPENED

Last year, Beck tried to win the NSA's endorsement by arranging a meeting with several high-ranking officials and a senior counterintelligence official from "a sister agency" who is an expert on the hostile nation's spy service.

"At the briefing, the sister agency officer gave a technical summary of the things the host country does to people that could harm them seriously," said Beck, who can't fully describe the meeting because it was classified.

"Afterwards, he sent me an email saying it was a 'no brainer' that this attack happened to me."

The NSA declined to discuss the briefing.

But the agency's director of security and counterintelligence, Kemp Ensor, emailed the NSA's then-chief of staff in August 2016 saying that he agreed that Beck's injuries were work-related - and that the NSA should convey his opinion to the Labor Department, Beck said.

Zaid, Beck's attorney, said he asked the NSA to hand over Ensor's email to the Labour Department.

But Zaid said the NSA rejected that request because it viewed the email as a personal opinion - not the official agency stance.

The NSA declined to make Ensor available for an interview, nor would it show The Washington Post his email, saying that "it contains classified information and equities of other intelligence community partners which would be inappropriate for us to discuss."

THE RETIREMENT CHAT

Beck retired last December after nearly 30 years at the NSA. He was entitled to a ceremony at NSA headquarters with a military colour guard.

Instead, he opted for cake in his Maryland office and, during his speech, joked that he felt like he had a career lifted from the pages of a Tom Clancy novel.

Except for a few friends and his bosses, hardly anyone knew of his unresolved battle with the agency.

After work, he and several dozen colleagues headed to the Rams Head, a favourite NSA haunt, where one longtime official approached him.

"It was a senior executive at the NSA. We couldn't talk much because we weren't in a secure facility," Beck said, "He said to me, in his opinion, that my injury was work-related."