Claudia Ackley believes in Bigfoot.

It’s led to ridicule and harassment and anxiety, but she still believes. She knows that some people think she’s crazy, but she still believes. It might even mean that cars with government plates are following her — she’s not sure, she’s got a picture of one of their license plates — but she still believes.

And now she wants the state of California to believe, too.

After her most recent sighting, the 46-year-old mother of two sued the California Department of Fish and Wildlife to get it to recognize Sasquatch — the enormous, hairy, humanoid creature, or creatures, allegedly seen by thousands of eyewitnesses — as an actual species. A spokesman for the department would not comment on ongoing litigation. Her first court hearing is set for Monday, in San Bernardino.

It might be easy to mock Ackley or call her a publicity-seeker. But speaking to her, she comes across as a completely sincere and polite person. She is proud of her daughters and friendly. She seems to be genuinely grappling with something huge and unsettling. And she isn’t asking for monetary damages.

All she wants, she says, is to let people know that something is out there, and it isn’t friendly.

Last March, Ackley was out for a hike with her two daughters, ages 14 and 11, near Lake Arrowhead, Calif. She says they were at a trailhead with their dog when one of her daughters saw something that made her freeze in her tracks.

Claudia ran forward and saw it, too: what she says was an alpha-male Sasquatch, looking back at her from behind the split of a tree. She got her daughters and got out of there. They were all terrified, she says.

On her way back, she found out one of her daughters had been taking a video at the time.

The video lasts only a few seconds, and it’s unclear. Ackley’s daughter says, “I swear to God . . . Mom?” The dog walks in front of the camera. There is a dark space in the trees. It might be a shadow. It might be a bear. It might be nothing.

But Ackley is adamant: “I swear to God, on my life, we ran into a Sasquatch.”

She called the state Department of Fish and Wildlife, which sent out an investigator. She showed the video to the investigator. She says she was told she saw a bear.

Ackley scoffs at that. “My daughters have seen bears. They’re not scared by bears.”

This was not Ackley’s first sighting, either. She says she’s seen the creatures multiple times over the years, the first time up close in Washington state, during a Bigfoot trek arranged as a vacation with her then-husband in 2014. She saw what she thought was a small, 5-foot-tall Bigfoot in the trees and locked eyes with it. She even made a plaster mold of an alleged footprint.

That sighting “changed my life,” she says now.

“I realized at that point, looking at the creature, that there’s so much of life that we don’t know. Life is so beautiful, and I’m wasting my years,” she says. “I lost 125 pounds and decided to get a divorce . . . It motivated me to chase my dreams and live my life.”

It doesn’t matter to her that there isn’t much of what scientists or courts would call evidence. Or the fact that even though nearly everyone carries an HD video camera in their pockets now, the best footage of Bigfoot is a nearly 51-year-old film. That DNA evidence collected so far has been shown to be from humans or bears or other animals. Or that nobody has ever produced a Bigfoot body, or even a bone.

Belief and facts, however, are different things, as Michael Shermer, an author, professor and publisher of Skeptic magazine, says. For Ackley to win in court, she’s going to need more than just eyewitness accounts, Shermer warns.

“You can’t sue the state of California to protect a species if you can’t prove the species exists,” he says. “That applies to everything from a snail to Bigfoot. You can’t just show up at a conference and say, ‘I saw this incredible thing at 3 a.m. on a camping trip, can I name it?’ No. You have to have a body.”

Ackley says she will bring a mountain of evidence to court. In addition to her video, she says she has new DNA analysis, as well as the testimony of Robert Gimlin, one of the men who took the famous 1967 footage of Bigfoot.

Ackley admits she’s tired of the skepticism and ridicule. She’s having trouble getting a lawyer to go to court with her (she filed the suit herself). And she finds the questions from reporters and other people draining.

But she still believes, and hopes her effort might keep people safe.

“They’re supposed to be there to protect the public. They’re not doing their jobs,” she says. “If I can save one life, it will be worth it.”

Bigfoot, she maintains, is dangerous. And people’s lives are at risk. This is not a friendly, shy, vegetarian creature who runs away at the first sight of humans. This is a potential killer.

For proof, she points to a murky world of YouTube videos and podcasts featuring second-hand stories from witnesses who claim they were attacked by Bigfoot, or at least a creature a lot like Bigfoot. In these accounts, Bigfoot attacks people and maybe even kills them.

It’s hard to find any corroboration — or even any names — to go with these stories. But Ackley still believes in them. “It’s my opinion,” she says. “I’ve never researched it. I believe it’s true.”

In this way, Ackley is like a lot of other people. Most of us have a relative or friend who believes in one conspiracy theory or another. It’s almost impossible to convince someone to let go of a belief once they’ve latched onto it, whether it’s the idea that Bigfoot exists, that GMOs cause cancer or the elaborate conspiracy of a secret child-abuse ring in the basement of a Washington, DC, pizza parlor.

Shermer says the way to talk to people about these things is to respect them, even if you don’t necessarily respect their beliefs.

“First of all, you have to listen to them,” he says. “You have to show respect. Ask questions. Ask them what it would take to change their minds.”

As for Bigfoot, he says, “There’s no conspiracy. Biologists would love to find another bipedal primate. It would be the find of the century.”

Even without a body, Ackley is not giving up.

“If you think you intimidate me after being face-to-face with an 800-pound creature?” she says. “Well, you don’t.”

No matter what, she believes.