He had been transferred from prison to prison, each with a higher level of security than the last, and now, in the most secure of them all, Ismail Royer was quickly finding out that the men in the neighboring cells were some of America’s most notorious extremists.

Terry Nichols, an accomplice in the Oklahoma City bombing.

Eric Rudolph, who bombed abortion clinics and the Atlanta Olympics.

Richard Reid, the shoe bomber.

It was Reid with whom Royer – convicted for his role in the “Virginia Jihad Network” in the “paintball terrorism” case – would eventually begin a lengthy correspondence in 2010 that would theologically and philosophically explore how terrorists justify their acts of violence.

Why, Royer asked, do terrorists kill civilians? Doesn’t that just bring more foreign soldiers to the Middle East and make a world more hostile to Muslims?

“The answer is that the benefit is in the fact that they cause damage to the Kufaar and place fear in their hearts and show the Muslims that they are not invincible,” Reid wrote Royer, using a word that means “disbeliever.” “Furthermore, they are the only means of inflicting any major injury on them.”

The dozens of letters, which Royer shared with The Washington Post, gave Royer an unfiltered insight into the terrorist mindset that he would bring out of a federal supermax prison in Colorado and into a Washington, D.C., nonprofit, where this spring he began a new career in extremism – this time, as an advocate against it.

REDEMPTION PHENOMENON

Royer’s apparent transition illustrates what has become a nascent phenomenon in America as the struggle against radical Islamists nears the end of its second decade and more people convicted of terrorist-related crimes approach their release dates.

Last year, George Washington University’s Program on Extremism hired Jesse Morton, once an al-Qaida recruiter, to research Islamist radicalization, before he was arrested earlier this year on a drug charge. Then Bryant Neal Vinas, who joined al-Qaida and advised in a terrorism plot before becoming an FBI informant, told a judge in May that when he is released this summer, he would like to become a counterterrorism analyst to “turn a bad thing into a good thing.”

Conversion as redemption has long been baked into the American narrative. Reformed gang members counsel at-risk students in urban high schools. Former white supremacists show extremists how to think differently. But in the United States, reformed terrorists advocating against terrorism represent something new.

“All over Europe, this is very common,” said Lorenzo Vidino, director of George Washington University’s extremism program. “You have former jihadists, and it’s a dime a dozen.” They start organizations. They consult government agencies on counterterrorism tactics. There’s more in Europe, Vidino said, because “the problem is bigger. … And the justice system is different. A lot of guys spent two or three years in jail, and in the states, for the same offense, you get 15 or 20 years.”

That’s what Royer got. He went away in mid-2003 and came out in late 2016, and in the in-between he saw fellow prisoners radicalize, and he came into contact with numerous terrorists. He observed as the ideology of his fellow inmates evolved from Osama bin Laden’s style of jihad – careful, methodical planning – to the barbaric, chaotic terrorism that characterizes the Islamic State. And now that he’s out, he says he’s ready for the next step in his own evolution.

“I’ve learned a lot through this whole thing,” said Royer, now 44, a man with a short-cropped beard and hardened features. “It would be a critical mistake not to hear what I have to say.”

CHANGED TO ISMAIL IN HIGH SCHOOL

The son of a photographer and a teacher, Royer grew up in suburban St. Louis, where even at a young age he was drawn to extremism, despite being raised in circumstances that were anything but extreme. His hometown, Ballwin, promotes itself as a “stunningly beautiful suburb” with the lowest violent crime rate in Missouri.”

In high school, Royer was attracted to the punk-rock crowd, among which one friend recalled there was always something in Royer that made him want to go farther than others.

“One day, he was, like, ‘You know what? … One day we’ll both be in the situation of being at the bottom of the pile with cops whaling away at us with their billy clubs,’ ” Chris Coleman recalled. “But in the back of my head I was, like, ‘Hell, no. I will do what it takes to stay out of that.’ And he would be right there.”

Coleman watched as that psychology worked its way from talk to action. Royer, who had converted to Islam after reading Alex Haley’s Malcolm X autobiography, changed his name from Randall to Ismail and left for his freshman year at American University. He flipped on the television one day and saw scenes of Muslims under attack during the 1990s Bosnian war. Feeling restive and useless, he made a decision that would put his life on a different course.

He left for Bosnia, joined the mujahideen, fought several battles, became more and more enamored of the militant life, turned 21, brought home to Virginia a Bosnian wife and came to the attention of authorities.

According to prosecutors, he went overseas again in 2000, this time to Pakistan, where he met with Lashkar-e-Taiba, a militant Islamist group that U.S. authorities later classified as a terrorist organization.

When he came back to Virginia, he started playing paintball in the woods with fellow Muslims whom he encouraged to join Lashkar-e-Taiba. Then followed the terrorist attacks of Sept. 11, 2001, and he distributed a message by a Lashkar-e-Taiba leader that condemned the “mass killings” but said it was “time to gather against the non-Muslims.” So he helped the paintball friends – who planned to fight the U.S. military in Afghanistan – connect with Lashkar-e-Taiba, and off the pals headed for Pakistan.

After flying to Bosnia, where he failed to get a visa into Pakistan, Royer returned to the United States and was indicted for “conspiracy to train for and participate in a violent jihad.”

Years later came ADX Florence, a supermax prison in Colorado known as the “Alcatraz of the Rockies.” It was here, in solitary confinement, that he used his time to reflect, undergoing a period that some experts say is vital to the reformation process.

What Royer said he thought about: Richard Reid, whom he met in the exercise yard and whom he classified as a different type of jihadist than himself. Royer believed in politically motivated violence between military combatants, but said he found attacking innocents reprehensible, and now here was someone who had tried to blow up a plane full of passengers. He had to find out why.

“I apologize for raising my voice in our discussion today,” he wrote in a letter passed to Reid through an inmate. “But I am somewhat emotional on this issue. … The issue of attacks on civilians. The issue of attacks by people who sneak into other lands, or who attack their land of residence, pretending to be law-abiding and at peace.”

“Jihad becomes ‘dutiful’ when the enemies attack the lands of the Muslims,” Reid wrote him back.

“It is not the object of Islam to annihilate people, but to guide them to the truth,” Royer said.

Royer spent days thinking about the letters, and then a realization hit him: “They’re portraying themselves as champions of Muslims when, in reality, they are the criminals.” he said, recalling what he had thought.

Royer, released in December 2016, felt he had awakened.

DIVERSE REASONS FOR IDEOLOGY

A few months after Royer got out, a former interrogator at the Guantanamo Bay prison named Jennifer Bryson saw a blog post on American Muslims she found interesting.

Bryson, now the director of operations at the Center for Islam and Religious Freedom, sent the author a friend request on Facebook, and a little later, after he had accepted her request, she saw a newspaper article about him.

She wrote Royer a message asking if he wanted to meet. There was so much about him that seemed familiar from her years at Guantanamo – “the most radical encounter I ever had with humanity,” she said – when she came to recognize the diversity of ideology among those who had been ensnared by the war on terror.

They met on the roof of the Islamic center’s building and talked for hours. That evening, she offered him a job at the center.

“He has insight into Islam and Muslims today, and that is essential to our work reaching out to Muslims … especially political Islamists,” she said.