Ralph Gilbertsen says the CIA has been stalking him for two decades. He believes in Bigfoot. He has seen a UFO.

And he wants his guns back.

Richfield police came to his door one day last year and took them away. Now Gilbertsen, a 74-year-old former security guard and Marine Reservist, is in court to force police to return the three handguns they seized.

His case raises the question of how to balance mental illness with the Second Amendment right to bear arms.

He has alarmed Richfield police, city officials and managers of his apartment building with a series of letters alleging constant and escalating harassment by the CIA.

But Gilbertsen has a state-issued permit to carry that’s good for another three years. He has no criminal record, and none of his letters threatened violence toward anyone. He usually gets around by bus, carrying his Smith & Wesson .40-caliber auto pistol because of its compact profile.

Ralph Gilbertsen stepped over and around documents and other objects on his living room floor last week. His attorney says police had no right to take his guns over what amounts to his beliefs.

“To me, it’s just a common-sense precaution,” Gilbertsen said. “Criminals don’t announce their intentions to you.”

In his letters, Gilbertsen identified specific residents and staffers at his apartment building as CIA agents, and warned that “they will lie and deny it.” He also identified specific Richfield police officers as CIA spies.

In neat, precise handwriting, he keeps a list of the license plate numbers of more than 75 vehicles that he believes have followed him recently.

“There are literally hundreds of CIA spies in Richfield alone that harass me,” he wrote in one letter. “There are thousands of these people in the south-suburban area. I am certain I will be murdered some day.”

Cops as psychologists

When three Richfield police officers knocked on Gilbertsen’s door last May, they were there at the request of Hennepin Community Outreach for Psychiatric Emergencies (COPE). The 30-person agency is a sort of SWAT team for mental illness, handling more than 13,000 cases last year, about one-third of them in person.

The managers of Gilbertsen’s apartment building called COPE after his latest series of letters. When they warned he might have guns, COPE called for a police escort.

Lt. Mike Flaherty, a Richfield Police Department spokesman, said officers are often forced to make snap judgments about an individual’s mental health.

“The street cops nowadays have to be a psychologist,” Flaherty said. “People don’t wear nameplates saying ‘paranoid schizophrenic.’ So the police have to go in there and make judgment calls.

“Is he crazy dangerous or is he the crazy uncle? We have to make that decision and let the legal system sort it out.”

In Gilbertsen’s case, Flaherty said, police acted properly in seizing the weapons. In addition to the .40-caliber pistol, they took his Smith & Wesson .357 magnum and an RG .22 revolver.

“I’m confident our officers seized the weapons with the best intention,” Flaherty said. “It was a mental health issue, and I think the cops responded appropriately. The process is being followed. If the court rules that we have to return his weapons, then we will return them.”

Police can never be entirely sure when someone will misuse guns. For example, before Brian Short killed his wife, three children and himself at their Lake Minnetonka home in September, there was little reason for anyone to suspect he’d turn violent.

‘An unusual situation’

In person, Gilbertsen — his friends call him “Gil” — is friendly and talkative, eager to share his thoughts and opinions on various topics. He grew up in Richfield and graduated from high school there. In court documents, he’s described as suffering from “a mild bipolar condition that is well-controlled.”

Gilbertsen has lived in numerous places across the country, working as a taxi driver, preacher, armored car guard, funeral home attendant and Wal-Mart greeter. He moved back to Minnesota in 2000 and has lived in Richfield for the past three years, getting by on about $900 a month in Social Security payments.

Gilbertsen calls himself a proud patriot and a Christian whose biblical beliefs forbid him from lying or injuring anyone. He said he’s handled guns all his life and knows how to use them properly. His psychiatrist sent a letter to the judge saying that Gilbertsen is compliant with his medications and poses no danger to himself or others.

That leaves a case, according to Gilbertsen’s attorney, in which police took away a citizen’s guns simply because of his beliefs. They’re unusual beliefs, acknowledged his attorney, Paul Baertschi.

“He’s what some people would say is a conspiracy theorist. It is an unusual situation,” Baertschi said. “But really, the police acted unilaterally in deciding that a person who has these beliefs can’t be trusted with a gun. And so they just took them, without a warrant.”

In a court filing, Baertschi wrote that Gilbertsen “is an able-bodied senior citizen who lacks the physical strength to defend himself from an attack and has the constitutional right under the Second Amendment to have a weapon for personal protection. The police have no right to confiscate his weapons based on the speculative worries of anyone.”

Citing Jesse Ventura

There’s no decision yet in Gilbertsen’s case, but he appears to have a good chance of getting his guns back.

Minnesota law allows the seizure of firearms on mental health grounds only if an individual has been committed to a mental institution or has been ruled by a judge to be a public danger. That requires a legal finding that the person has tried to harm others or that there’s “a substantial likelihood” of harmful behavior.

Gilbertsen notes that many Americans share his concern about government spying, including Edward Snowden, the former CIA employee who revealed widespread surveillance programs run by the National Security Agency.

As further proof, Gilbertsen points to former Gov. Jesse Ventura’s book “American Conspiracies,” which he owns and refers to frequently.

“A lot of people believe these things, but they don’t want to talk about it,” he said. “I could see people being skeptical if I was saying something really outlandish, like space aliens with big heads were visiting me every night. But nobody can believe the CIA is squeaky clean.

“The people who think these things can’t happen, I think they’re the ones living in Alice-in-Wonderland world.”