TAMPA — Like most people, Watson Fincher was shocked to hear that a neo-Nazi turned jihadi stands accused of killing his two Tampa Palms roommates, and that a fourth roommate told federal agents he, too, was a neo-Nazi — with bomb materials and a plan to target infrastructure.

But unlike most people, Fincher, 24, who lives in the Houston area, says he knows both the defendants — Devon Arthurs, 18, charged with two counts of murder in the shooting deaths of his roommates, and Brandon Russell, 21, a Florida National Guardsman accused of illegal possession of explosives.

"I thought maybe they would blow up a mail box or beat someone up and go to jail for six months," Fincher said. "We never thought it would be something like this."

On Friday, officers investigating the double homicide found a garage stocked with bomb materials, leading to the federal explosive charges against Russell, who kept a framed photo of Oklahoma City bomber Timothy McVeigh on his dresser.

Arthurs, according to Fincher, owned several guns, including a Romanian-made variant of the AK-47 rifle called a WASR-AK.

But neither man exhibited this level of violence before, Fincher said.

"Many guys that started with the Nazi stuff were forced to grow up and leave it behind once they got jobs and girlfriends and the like," he said. "We had hoped Devon and Brandon would do the same."

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Arthurs and Russell were longtime friends, both from the Orlando area, who met online in political chat rooms largely dedicated to white nationalism, Fincher said. That's where Fincher came to know them, four years ago, because he, too, subscribed to the chats. Fincher met Arthurs in person on one occasion but never met Russell.

Fincher reached out the Tampa Bay Times on Monday after reading an online report about the arrests. He spoke to a reporter by phone Monday night.

Efforts to contact the families of the two men Monday by phone, through social media and in a visit to the Orlando area proved unsuccessful. Fincher said Russell's parents have a home in the Bahamas.

Arthurs and Russell had much in common, Fincher said. Both were from troubled homes with parents unhappy about their sons' support of neo-Nazi causes. Both had trouble dealing with people. Both were adrift and found comfort in the online community of like-minded people.

"Devon came from a really bad home," said Fincher, who referred to Arthurs by his first name.

"Brandon's family was not happy with his views and kicked him out of his home."

Arthurs first joined the online conversations when he was 14, Fincher said. Russell was a few years older, about 17, when he was drawn in by the ideological exchange.

At first, it was just disillusioned young people sharing their thoughts. But words eventually evolved into actions, Fincher said.

About 18 months ago, the two young men pulled off what Fincher described as a "stickercaust," slapping labels with swastikas and anti-Semitic slogans on school campuses in central Florida.

The pair loved the resulting attention, Fincher said, especially when their exploits received news coverage.

Police, Fincher said, never found the vandals. But Arthurs' parents figured it out and were furious.

"He got in trouble," Fincher said.

It was the beginning of a downward spiral, Fincher said — one that isolated Arthurs from a friend who later took his own life. Arthurs blamed himself, Fincher said.

Russell was described as a smart young man with a keen interest in science.

"There are YouTube videos of him playing with homemade Tesla coils," Fincher said. "He was one of those geniuses."

Russell was also fascinated with rocketry and talked about making one for a science project, Fincher said. Russell told investigators he possessed the bomb-making materials because of his academic interests, according to a federal criminal complaint.

Known widely by his online persona, "Odin," the Norse god, Russell wasn't always taken seriously by the hardened white-power crowd, Fincher said.

About a year or so, Russell traveled to England to meet up with other white nationalists.

"But he made a fool of himself," Fincher said. While in the act of committing vandalism, Fincher said, Russell gashed his own hand with a knife.

Still, Russell managed to rise to lead the "Atomwaffen Division," a small, loosely affiliated white supremacist group that has been deemed a hate group by the Anti-Defamation League and the Southern Poverty Law Center. Members are mostly connected through the internet, according to the League, and focus on distributing white supremacist fliers urging students to join local Nazis on college campuses around the country.

In October 2015, Odin posted a summary of the group's mission on the website ironmarch.org, which describes itself as a "Global Fascist Fraternity" and urges "race war now!"

"We are very fanatical, ideological band of comrades who do both activism and militant training," the post read. "Hand to hand, arms training, and various other forms of training. As for activism, we spread awareness in the real world through unconventional means. (keyboard warriorism is nothing to do with what we are.)"

According to the post, the group has "a large concentration" in Florida and "various smaller chapters" throughout the United States.

Fincher said the group claimed to have 20 to 40 members, some of whom, like Russell, were either in the military or thinking of joining.

"They join the military mainly to gain fighting skills," Fincher said. "A lot came from bad homes, or if they didn't, had zero direction and dead end jobs."

Russell made Arthurs his second-in-command, which caused friction within the group. Members didn't much care for Arthurs.

Russell continued his leadership of the group while in a Florida National Guard uniform, Fincher said.

Russell is a private first class with the guard, assigned to the 53rd Brigade Special Troops Battalion in Pinellas Park, said to Maj. Caitlin Brown, a guard spokeswoman. He joined in February 2016 and his job was maintaining communications systems.

Russell was never sent overseas with the guard, Brown said.

"He would call us when he was in the barracks," Fincher said. "He liked the military part of it."

In the last year or so, Arthurs began a dalliance with Islam, Fincher said. On ironmarch.org, Arthurs went by the handle "theWeissewolfe" and listed his affiliation as "Salafist National Socialism." Salafism is an ultra-conservative branch or movement of Sunni Islam.

Arthurs conversion caused friction among his neo-Nazi associates, many of whom openly mocked him online. But Fincher described the shift as a case of Arthurs trying on a new persona.

"I know this seems like a crazy red flag, but he would jump from one ideology to the next," Fincher said. "He was an atheist. Then Catholic. Then Orthodox Christian. Then Nazi. Then Muslim. He latched onto the esthetics of anything that looked cool."

Arthurs also spent time on messaging boards for the Microsoft-owned video game Minecraft, which has sold more than 105 million copies, and reached out to some players there to encourage interest in Islam, Fincher said.

Though now accused of two murders, Arthurs mostly threatened violence only to himself, Fincher said.

"This is so out-of-left field. We all knew he had problems and in the past six months we tried to get him to seek mental health treatment. He never talked about violence, but talked about killing himself. But he said he couldn't do it because of family."

In the past few months, Arthurs seemed to be turning his life around. He was in better health, working out, even talking about getting a job, Fincher said.

But during a recent Skype conversation, Fincher said, he saw something that now appears to have been a bright-red flag.

"He would play with his guns on camera and he pointed it at his roommates one time," Fincher said. "Last week, we kind of had a laugh about that, but looking back, you can imagine ..."

By Sunday night, the Atomwaffen Division chat board lit up as news of the murders began to reach group members and others from the broader neo-Nazi movement. They mourned Himmelman and Oneschuk as "fallen Aryan brothers" and used racist epithets to describe Arthurs as a Muslim traitor.

By Monday morning, commenters were lamenting Odin's arrest. They showed concern that the Atomwaffen Division, with its leader and a member regarded as a traitor in government custody, is vulnerable to government infiltration or elimination. Some commenters said Russell should have excommunicated his friend long ago.

"Odin was sympathetic towards Salafism and its (sic) come back to ruin his life basically," one commenter says, "his kidness (sic) and loyalty towards his friend was repaid with treachery."

Times senior news researcher John Martin and staff writers Tony Marrero and Dan Sullivan contributed to this report. Contact Howard Altman at haltman@tampabay.com or (813) 225-3112. Follow @haltman