A former Canadian army reservist under investigation for alleged "racist extremist behavior" has been missing for more than a week, and authorities in Canada and the U.S. are warning people to stay away from him.

Patrik Jordan Mathews, 26, was last seen by his family members on Aug. 24 in Beausejour, the Royal Canadian Mounted Police said in a press release. He was reported missing two days later.

His vehicle was found Monday afternoon on a rural property in Piney, which is in the Canadian province of Manitoba along the Minnesota border. The RCMP said they believe the vehicle may have been parked there for about a week.

Police in Canada and the U.S. warned people not to approach Mathews, a former master corporal with the Canadian Armed Forces, and said to contact authorities immediately if they see him.

Patrik Mathews. Royal Canadian Mounted Police

"He is listed as a missing person," the Roseau County Sheriff's Office in Minnesota said in a Facebook post. "**DO NOT APPROACH**"

The RCMP said they believe Mathews "may be under a significant amount of pressure" and anyone who sees him should "avoid engaging with him."

According to Global News, Mathews allegedly has ties to a neo-Nazi group and his disappearance came days after the Winnipeg Free Press published an article alleging that he was recruiting for a white supremacist group.

A spokesperson for Canada's Department of National Defence told NBC News in a statement on Friday that the Canadian Armed Forces is aware of "possible racist extremist activities" by Mathews and the matter has been under investigation for several months.

Mathews joined the Armed Forces as a reservist in 2010 and was a combat engineer at a base in Winnipeg. As of Aug. 30, he was no longer a member of the Armed Forces after he submitted a request to leave a few months prior.

The spokesperson declined to say if his request to leave was in connection to the investigation.

"It is completely unacceptable for a CAF member to participate in an activity or have membership in a group or organization that the member knows, or ought to know, is connected with criminal activities, promotes hatred, violence, discrimination, or harassment," the spokesperson said.

As part of his release from the army, Mathews returned all of his military equipment including his uniform. He was never issued any weapons, the spokesperson said.

The RCMP said there are no warrants for Mathews' arrest or pending charges against him and this is being treated as a missing person investigation.