It takes a good while for J. Reece Roth to answer the door at his home on the west side of Knoxville. A former electrical engineering professor at the University of Tennessee at Knoxville, where he was also the director of the Plasma Sciences Laboratory, Roth will be 81 in September and has hip, knee, and heart problems, which have slowed him down quite a bit.

Of course, the four years he spent in prison for violating the Arms Export Control Act didn’t do him many favors, either.

Former students and contemporaries describe Roth as something of a pioneer in the field of plasma physics. When he was accused in 2006 of divulging sensitive technical data to two foreign nationals, Roth had been working on research for the U.S. Air Force, developing thrusters that used atmospheric plasma gas—something typically created only under highly controlled laboratory conditions—to improve the flight performance of unmanned aerial vehicles, or drones. It’s been almost 15 years, but Roth is still noticeably upset about the way things went down.

“I was handled by the government in such a way that has basically intimidated researchers all over the country as far as carrying forward applications [of my technology],” he says.

The twist is, none of what Roth revealed was classified. And the foreign nationals weren’t spies, they were grad students. But as is typical with sensitive DoD research, foreign citizens were explicitly forbidden from working on the project without a special license from the federal government. By allowing Ph.D. candidates Xin Dai, from China, and Sirous Nourgostar, from Iran, to participate, Roth violated a once-obscure corner of U.S. export law that considers describing, demonstrating, or explaining certain things to a foreign citizen, even one that’s standing next to you in Tennessee, to be an illegal “export.”

Another of Roth’s violations resulted from a trip he took to China with a laptop containing files from the Air Force project, even though forensic tests later showed those files were never opened while he was there. During that same trip, he asked a student to email him some files. Roth said he was having trouble connecting to the internet, and told the student to send them to the account of a Chinese professor at the university he was visiting.

“ Even a blank sheet of paper from that research was export-controlled. ”

After six hours of deliberation, the jury convicted Roth on 18 out of 18 counts, including conspiracy, wire fraud, and exporting defense articles and services without a license. The two foreign graduate students were never accused of wrongdoing, nor were they ever suspected of any.

As a former associate of Roth’s told The Daily Beast: “It’s simple. Because this was a military contract, it was a contractual designation [to restrict participation to U.S. citizens only] and that’s what screwed everything into the ground. Because even a blank sheet of paper from that research was export-controlled.”

American counterintelligence officials have long warned about spies on campus, and according to recent congressional testimony by current and former U.S. counterintelligence officials, foreign intelligence services are more active than ever within the academic community. There is a “small but significant percentage” of international students and faculty sent to the U.S. to steal military and civilian research, as journalist and author Daniel Golden testified before the House Science Committee in April, citing a DoD finding that the use of academics by foreign intelligence agencies has tripled over the past two decades.

“Without going into details that I cannot divulge, I can reinforce the fact it is a longstanding issue,” retired CIA operations officer Charles Goslin told The Daily Beast. “Typically, universities get full compensation from the governments sending those students to the U.S. to study and then return with cutting edge research and IP. So, the incentive to keep the cash coming in outweighs the incentive to closely monitor the students from those countries.”

As the Trump administration threatens to impose what could turn out to be the most prohibitive restrictions on foreign students’ access to U.S. universities in modern history, exclusive new interviews with figures from the Roth case shed additional light on just how serious the government is about keeping American defense technology out of the wrong hands.

Roth was born in 1938 in Chartiers, Pennsylvania, near Pittsburgh. He got his bachelor’s at MIT before going on to Cornell for his doctorate. Roth then worked at NASA until 1978, when he left to teach at the University of Tennessee at Knoxville. Formal and a bit stiff, yet quite friendly and accessible, Roth speaks in a rich baritone and chooses his words carefully.

Although he rarely gets away much anymore, Roth traveled to China extensively in years past. Two of his books had been translated into Chinese, and he always got a steady stream of applications from students there who were eager to study with him. Roth speaks extremely highly of the Chinese scientists he has met, and was made an honorary professor at the renowned University of Electronic Science and Technology of China in Chengdu and Beijing’s elite Tsinghua University in 1992 and 2006.

China is as much of an espionage threat, if not even more so, than Russia, a former intelligence operative from a country in Eastern Europe told The Daily Beast.

“They are extremely effective in using their former citizens, or Americans with Chinese roots or relatives in China,” the ex-spy said. “They have no limits with money, and the Chinese government can guarantee resettlement to China and financial support if the person they recruited is captured or busted by local authorities. And of course, there is no extradition from China.”

The Chinese government has also established Confucius Institutes, which trace a direct link to China’s Communist Party, at more than 100 universities across the U.S. counterintelligence officials have warned that the Confucius Institutes can be used for espionage, and as former intelligence analyst Peter Mattis recently told The Washington Post, they are part and parcel of the Chinese Communist Party’s “united front” propaganda efforts against the party’s detractors.

In fact, Chinese influence is of such concern to U.S. counterintelligence officials, they reportedly warned Donald Trump son-in-law and senior adviser Jared Kushner last year that Wendi Deng Murdoch, ex-wife of News Corp CEO and founder Rupert Murdoch, could be working for China’s intelligence services.

Surely aware that Chinese espionage does exist, Roth insists the intentions of his Chinese counterparts, by and large, were pure.

“The contacts I had were normal scholarly contacts with colleagues at universities in other countries who simply wanted to exchange information,” Roth told The Daily Beast in his first interview since being released from prison in 2015. “With the possible exception of my trips to China, the information transfer was pretty much two-way and I don’t think it was motivated by any desire to spy on, or take, U.S. technology.”

Needless to say, people targeted by foreign intelligence sometimes don’t know that they’ve been compromised. And spies often don’t look like “spies.” In the post-Roth era at UT, the administration advises students and faculty working on export-controlled projects not to even send documents to campus copy centers where foreign nationals might be working.

Universities have a challenge in blending a culture of academic freedom with restrictions on intellectual property, said Will Mackie, one of the two government attorneys who prosecuted Roth. Mackie emphasizes the importance of academic research to the U.S. economy, and says export control laws are not meant to restrict research, but to protect it.

Roth’s situation “was totally preventable,” his onetime prosecutor explained. “He never stated that he was totally ignorant of the rules, so that was not a defense... The concept is that he thought that these rules were unnecessary and he also tried to say that he knew this technology better than the regulators and it was something that he didn’t think should be controlled.”

Roth had a way about him that didn’t make people want to go to bat for him when he was hauled into court, others said. Daniel Max Sherman, who studied under Roth before going on to work alongside him, recalled Roth’s tendency to take credit for everything developed in his lab whether it was his idea or not, generating “numerous instances, even legal consequences, over whether or not he owned a certain piece of intellectual property.”

“Roth had this attitude that basically he had created something special and great,” Sherman told The Daily Beast. “He would go to these national conferences and tell people they were stealing his ideas, or that he had already thought of it and if they’d just read Chapter 7, Section 2 of his book…”

In Roth’s case, authorities had been tracking at least one of his two foreign-born graduate assistants from virtually the moment he first set foot on American soil.

Born in Tehran in 1976, physicist Sirous Nourgostar had always admired Roth’s work from afar. A graduate of Tehran’s Alborz High School, which was founded by American missionaries in 1873, Nourgostar arrived in the United States in August 2005 to study under Roth’s tutelage. Ultra-hardline Iranian President Mahmoud Ahmadinejad had taken office a few days earlier, and U.S.-Iranian relations were particularly tense.

Nourgostar told The Daily Beast he was questioned and fingerprinted by immigration officials upon arrival at Los Angeles International Airport. Although he had a valid F1 student visa, Nourgostar claims officers threatened to turn him away and send him back to Iran. For reasons he never makes fully clear, Nourgostar was eventually cleared for entry and made his way to Tennessee for the fall semester.

In the meantime, the FBI paid Roth a visit and asked about, among other things, the kinds of chemicals and instruments Nourgostar would have access to in his lab. A few days after Nourgostar got to town, he says he was also questioned by the FBI. Before they could get started, Nourgostar preemptively assured them that he wasn’t religious or observant. The agents cut him off right away, saying they weren’t allowed to talk about that sort of thing.

“ The head of the FBI team told me, ‘Look, I know who you are. All I can tell you at this moment is that this is not about you.’ ” — Sirous Nourgostar

Eight months later, while Roth was off lecturing in China, the FBI raided his lab. Nourgostar watched a team of armed agents label, photograph, and cart away everything from computers to lab notebooks as evidence. He says he had no idea why the FBI was there, and they wouldn’t give him any details.

“I thought maybe I did something wrong, I was very scared,” Nourgostar recalled. “Then the head of the FBI team told me, ‘Look, I know who you are. All I can tell you at this moment is that this is not about you.’”

When Roth flew back to the States from China a few days later, customs agents in Detroit pulled him out of line and copied the contents of his laptop’s hard drive. Nourgostar said Roth called him before catching his connecting flight home to Tennessee, explaining that he had been stopped and questioned. He asked how things were back at the lab, and Nourgostar broke the news to him that the FBI had confiscated most of its contents.

When Roth’s connecting flight landed in Knoxville, agents from the FBI, Customs & Border Protection, and the Department of Commerce seized the laptop itself and a thumb drive. After a two-hour interrogation, Roth said he was allowed to go home; he was not arrested at that time.

Months went by while the FBI interviewed everyone in Roth’s orbit. According to an as-yet unpublished memoir by Daniel Max Sherman, a friend of his who worked at the Pentagon sent an email encouraging him to try not to worry too much.

“It’s uncomfortable, but you did nothing wrong; Roth did… The authorities will figure it out. Unfortunately, it will cause you some distress for a period of time and your work will be on a watch list,” the friend wrote.

Roth wound down whatever research he had left, reviewing papers for scientific journals, and getting ready to retire. He vowed to fight and beat this thing. But Nourgostar had been called to testify before a grand jury and knew that Roth was actually in very deep shit.

“I wasn’t supposed to talk or give any feedback about participating in the grand jury, so I could not tell him anything,” Nourgostar said. “The way he was talking to us, that they don’t have anything, well, all of a sudden there was an indictment.”

Roth was given a time and date to turn himself at the FBI’s Knoxville Field Office to be formally arrested. Roth was handcuffed and fingerprinted; agents took a DNA sample.

“It was more like an office appointment with a physician than anything else,” Roth said. “I showed up at the stated place and time; there weren’t any sirens, I wasn’t dragged out of my house or anything like that.”

Nourgostar claims the FBI told him during questioning that they viewed this case as one that would send a “strong message to other universities that we are serious about this kind of thing.”

“ There are a few people willing to risk prison for their principles. He’s one of them. ” — Thomas Dundon

The drone project “from the beginning had a component in it that I knew, something was not right,” Nourgostar said, “but at the time, I was a fresh student,” and felt that it would be better to not make any waves.

Nourgostar wound up taking the stand against Roth, calls his former mentor “an amazing professor I had in my life,” and described his short stint in Roth’s lab largely as “an extraordinary experience.”

“He was a true true teacher who wanted to have some sort of legacy left behind,” said Nourgostar. “I haven’t been able to find anyone else like that man.”

Nourgostar and others describe Roth as somewhat stunted emotionally, possessing almost childlike social skills.

He put himself at a disadvantage from the start, antagonizing the feds from the very beginning of the investigation, according to defense attorney Thomas Dundon, who represented Roth in court and received permission from Roth to speak openly to The Daily Beast about the case.

Immediately after he was stopped at the airport, but before he had hired Dundon, Roth began calling and emailing federal investigators to defend his position. That is, that academic researchers should be able to use the best and the brightest students as they wish, no matter where they’re from. The investigation would continue for the next three years.

“We started off with Dr. Roth having presented his perspective in the matter more than one time, and in writing on at least one occasion, to a variety of people,” said Dundon, explaining the enormity of the task he faced after Roth retained him. “I would not recommend any client do that.”

Roth, who said he had in fact submitted debriefing reports to the CIA after past trips to China, was personally outraged by the insinuation that he couldn’t be trusted to protect the integrity of his research, Dundon recalled. Using foreign nationals on a restricted military contract was bad, but Roth taking sensitive information on his laptop to China and having restricted material sent to him via email there was what really stuck in the government’s craw, said Dundon.

Roth lacked a full understanding of the internet, and didn’t appreciate the fact that his data could have been intercepted by the Chinese government, something we now know is standard operating procedure, Dundon said. Whether or not Chinese agents or any of Roth’s Chinese university colleagues actually got access to this material, Dundon doesn’t know.

“I don’t recall there being any proof, but I do recall that the government expressed concern about that,” he said.

“I admired Dr. Roth for being willing to stand up for his principles,” Dundon said. “I don’t see that very often in my business. A lot of people would perhaps say it was misplaced. Nevertheless, there are a few people willing to risk prison for their principles. He’s one of them.”

Daniel Max Sherman was a student of Roth’s at UT before going into business with him. Now 47 and living in Chattanooga, Sherman exudes an unmistakable cynicism about the world.

Born in rural Dayton, Tennessee, to a mom who had turned 18 only a few days earlier, Sherman never met his father. He got his contact info a while back, but never actually got in touch.

“I grew up with a long list of stepfathers, most of them with military backgrounds,” Sherman explained. “The first father I remember was a drill sergeant for the Army and he was not a nice man.”

Sherman, who is speaking publicly about the case for the first time, left home during his senior year of high school, primarily to escape his mother’s third husband, an alcoholic Marine Corps drill instructor. Sherman’s grandmother managed to cobble together enough money for him to attend UT, and one of his high school teachers gave him a few hundred bucks for textbooks.

Sherman was the director of plasma sciences at a small, publicly traded company in Knoxville called Atmospheric Glow Technologies (AGT). Roth was a minority partner. Located in a commercial park 20 minutes west of downtown Knoxville, the offices are less than a 10-minute drive from Reece Roth’s home.

AGT was spun off from UT to develop commercial applications for Roth’s plasma actuator design. In fact, Sherman, who co-owns the patent, says the actuator “in this particular form was a design that resulted during my Master’s in 1995. At that time, Dr. Roth was my advisor.” Roth reportedly offered to let Sherman take full credit, but Sherman, Roth, and a third collaborator are listed as co-inventors.

AGT existed with two basic funding mechanisms, Sherman explained. One followed the traditional commercial model, raising money from outside investors. The other came from the federal government. Sherman was the one who wrote the bulk of those proposals, generating most of the initial ideas after which he said other people’s names would inevitably also be “slapped on.”

“ As one of [my former colleagues] at Oak Ridge [National Laboratory] explained to me, ‘Daniel, I can’t send this pen to Iran.’ ” — Daniel Max Sherman

Still, the question remains: Why would Roth risk his reputation, his career, and his freedom just to hire a couple of foreign graduate research assistants? Is it really that hard to find competent American Ph.D. candidates?

“Dr. Roth’s lab was constantly filled with foreign nationals,” said Sherman. “His book had been translated into foreign languages and they respected him and most Americans couldn’t stand working for him, he was such an ass.”

Dan Golden, author of Spy Schools: How the CIA, FBI, and Foreign Intelligence Secretly Exploit America’s Universities, was the first person to interview Roth when he went to prison in 2012 and has written about the case extensively.

“I think it flattered his vanity to have students who had admired him from afar and who could remind him about what a major figure he was in China, because he’s not a man without ego,” Golden told The Daily Beast. “So, that’s the specific reason. More broadly, there’s a plethora of foreign graduate students in American science departments.” (He also points out the ironic disconnect between UT’s vigilance in turning in Roth while at the same time seeming less alert to the myriad issues posed by hosting a Confucius Institute on campus.)

It was Sherman who ultimately acquiesced to Roth’s demand that Xin Dai, his Chinese student, be hired onto the drone project. However, he insisted that all restricted material be kept away from Dai and handled by an American student, Truman Bonds. A noble concept, but one that unfortunately did not work in practice, according to Sherman.

As Dai neared graduation and Roth announced that he wanted Nourgostar to take his place, Sherman finally put his foot down.

“It had been made clear to me that it really wouldn’t be a good idea,” said Sherman. “As one of [my former colleagues] at Oak Ridge [National Laboratory] explained to me, ‘Daniel, I can’t send this pen to Iran.’”

When Sherman told Roth he would do whatever it took to block the hire, Roth sought support from the university’s supervisor of faculty research contracts. She advised Roth to speak to the school’s newly-hired export control officer, who was more than a little alarmed not only by the notion of hiring an Iranian national for a project that was very obviously subject to serious regulations, but also that a Chinese national had already spent a year illegally working on the project without anyone knowing it. Roth left for China, the export control officer called authorities, and that’s when everything began to collapse.

According to most everyone involved, Roth ignored multiple warnings from various people about his hiring of foreign students, insisting all the while that the university’s non-discrimination policy overrode federal export law.

During the trial, Roth flatly refused to consider negotiating a plea bargain, insisting he had done nothing wrong. The jury obviously thought otherwise, finding that Roth acted with the requisite intent.

“ The greatest damage, my friends would say, is that by the time I left prison, I had turned my back on invention ” — Daniel Max Sherman

Backed into a corner, Sherman agreed to plead guilty to one count of conspiracy to violate the Arms Export Control Act. The judge sentenced him to 14 months. He did his time as inmate #32207-074 at a federal prison camp in Florence, Colorado, alongside former Enron CFO Andy Fastow, who worked in the barbershop.

Sherman says he took the deal in hopes that he could “put this shitstorm behind me and try to eventually rebuild a life, which I haven’t.”

“What does a felon do when they get out of jail?” he says when asked if he still practices physics. “They do construction. I do remodeling and construction, that pays the majority of my bills.”

Xin Dai got his Ph.D. in electrical engineering in 2006, and now works as a patent lawyer in Palo Alto. He did not respond to multiple requests for comment. Sirous Nourgostar is working as a researcher in the University of Wisconsin Madison’s Department of Nuclear Engineering. Truman Bonds is the president of a firm in Knoxville, which is successfully commercializing a carbon fiber oxidation project Sherman says he started back at Atmospheric Glow. Reached by email, Bonds declined to comment.

Atmospheric Glow was charged as a company, and pleaded guilty to 10 counts of conspiracy. On April 1, 2008, the firm declared bankruptcy. A few months later, AGT’s assets were sold off to a Connecticut firm for $125,000 cash, plus $200,000 in stock.

In the end, Sherman fell just short of earning his doctorate. Once the federal investigation began, the Air Force stopped communicating with the AGT team. When the Ph.D. committee realized there would be no way for Sherman to publish his results, they told him it wasn’t worth going any further.

“The greatest damage, my friends would say, is that by the time I left prison, I had turned my back on invention,” Sherman said. “I found a wealthy philanthropist here in town who wanted me to take on a high-tech project kind of as a hobby, and I did that for a little while until he passed away, and I haven’t done science since.”

Both Sherman and Roth speak about their plasma research with noticeable pride, although they both say it has largely disappeared.

“I will tell you that all the inventions that we came up with, to this day are still not being discussed in the public literature,” said Sherman. “The technology could literally be 100 times more electrically efficient and 10 times stronger, but no one talks about it.”

“The technology in the U.S. has not advanced nearly as quickly and over as broad a range as I think it should have,” said Roth, who lists a number of civilian uses that haven’t yet been fully explored, including sterilization and decontamination in the medical and agricultural fields.

“At the time I was jailed, there were a bunch of tests showing that plasma actuators could reduce the drag on [wind turbine blades] up to 30 percent,” Roth explained. “In aerodynamic terms, that’s a big decrease in drag. Over the last 50 years, they’ve been spending millions to get the drag on airfoils down just a few percent at a time.”

“ If we can reduce the espionage and theft done by a small minority, we could get the benefit of the majority, who don’t. ” — Daniel Golden

On the other hand, Tom McLaughlin of the Air Force Academy says Roth’s technology, which he describes not as a brand-new discovery, but a clever “tool” based on the dielectric barrier discharge plasma first reported by Ernst Werner von Siemens in 1857, had already reached what he considers to be its practical limits, at least for his purposes.

“It was difficult to make it work at aerodynamic speeds of interest to us,” McLaughlin told The Daily Beast. “It would at very low speeds but the faster you got, the less effective it became. I don’t think the case led to the demise of the technology, we played out the technology and found it wasn’t doing everything we thought it would.”

Dan Golden appreciates the fact that Dai and Nourgostar have stayed to make lives in America, saying that this is precisely the point that people often overlook when they talk about the danger of espionage at U.S. universities: The great majority of Chinese (and other) students who come to the States and earn their Ph.D.s stay for at least five years after getting their doctorate. Some stay a lot longer than that, said Golden, meaning their inventions stay here, too.

“If you cut off China, you lose the benefit of all the research they do when they’re here. If we can reduce the espionage and theft done by a small minority, we could get the benefit of the majority, who don’t.”

The experience has obviously left an indelible impression on Roth, whose wife Helen watches TV in the other room as he recounts events more than a decade in the past like they happened yesterday.

Today, Roth’s life tends toward the ludditistic. He has a cell phone, but if he wants to put something in writing, he sends a letter. He has refused to get online since leaving prison for fear of “the potential misrepresentation of any kind of message they happen to come up with through these dragnets that they perform on people’s correspondence.”

Roth views his case as having been “politically motivated,” and doesn’t think investigators had the necessary level of scientific sophistication to fully grasp the nuances involved. If they had, he doesn’t believe he ever would have been hauled into court in the first place.

“Some of those prosecutors were involved in pursuing people who were producing bootleg liquor and that was the kind of prosecution that they seemed to go after,” Roth says. “I think they attribute China’s technical success to their stealing our technology, when in fact the Chinese are perfectly capable of developing and originating their own.”