Mathews, a member of the Canadian Army Reserve, had gone missing while he was under investigation for his involvement with a secretive neo-Nazi group called The Base. An undercover reporter found their interests included hating people of color, women, Jews, and queer people, and that they're “eagerly preparing for a race war.”

After the story, authorities raided Mathews’ rural Manitoba home on suspicion that he was amassing firearms and trying to recruit more Base members. (He’d already posted some pretty troubling stuff on the group’s encrypted messaging app.) Days later, he disappeared.

Back in September, an old pickup truck was discovered just on the other side of the Canadian border. Authorities thought maybe Mathews had crossed over somewhere near Roseau and ditched the truck about a week earlier. Minnesotans were advised Mathews was a dangerous missing person and that they should call the police or border control if they recognized him.

According to charges unsealed on Thursday, the FBI arrested Mathews and two other members of The Base in Maryland. They’d allegedly been en route to a pro-gun rally in Richmond, Virginia, and had cobbled together a homemade assault rifle and amassed hundreds of rounds of ammunition.

The FBI says Mathew’s cohorts, alleged Base members Brian Mark Lemley Jr. and William Garfield Bilbrough IV, picked him up near the Manitoba-Minnesota border last summer and drove him to their home state of Maryland. Lemley and Mathews then hopped over to Delaware, built the gun, and gathered ammo.

While testing it out at a firing range, they discussed dismantling the gun in case agents from the Bureau of Alcohol, Tobacco, Firearms, and Explosives ever caught on and dropped by, according to court documents.

“Um, if they show up here, we got other problems,” Mathews allegedly replied.

Mathews could face a maximum of 10 years in prison if he’s convicted of transporting a gun with intent to commit a felony—and another 10 if he’s convicted of being an illegal alien possessing a firearm and ammunition. Meanwhile, his friends Lemley and Bilbrough could face a maximum of five years for transporting him.

Some have commented that they were “surprised” how far Mathews got without being detected. For others, that surprise verges on disappointment.

“If Mathews had… pledge[d] allegiance to a group like ISIS, there would have been a much more intent manhunt for him,” Joshua Fischer-Birch of the New York-based Counter Extremism Project told CBC. “Hopefully, with this arrest, groups like The Base will be at the forefront of law enforcement efforts on domestic terrorism here in the United States.”