Rick Duncan had already announced his campaign for a third term as Chisago County sheriff when he resigned unexpectedly last month, citing medical issues.

But his decision to quit came only a day after he admitted to investigators that he had hatched a bizarre scheme involving him and a female sheriff’s office employee, according to documents released Friday by the Chisago County Attorney’s Office.

Duncan admitted that he wrote threatening letters last fall under the name “Control Freak” directing the employee to go with him to a training in Bemidji and stay overnight at a hotel together or risk harm to their families, the documents say. He directed the woman to refrain from telling her husband or reporting the matter to law enforcement or anyone else at Chisago County.

The woman ultimately refused to go and months later reported the ordeal to a supervisor, launching an investigation that the Chisago County attorney referred to an independent law firm.

The county attorney has referred the case to officials in Anoka County for review for criminal charges.

Duncan’s attorney, Marshall Tanick, said Friday that Duncan “was undergoing some health-related issues that led him to decide to retire. He is continuing to deal with those issues and appreciates the support that he has received from members of the community.”

Leslie Lienemann, an attorney for the woman targeted, said they will make decisions about any legal claims in the next couple of weeks.

In recent interviews with the Star Tribune, the woman described the toll that the stress of the ordeal took on her.

“From when it first began through the whole thing, my whole feeling was, this can’t be happening. This can’t be real,” said Michelle Jacobson, the target of the threats. “I’m still waiting for someone to say, ‘It was a joke. We punked you ...’ It was so bizarre.”

Duncan grew up in Chisago County and spent more than 20 years as a Minneapolis police officer, rising to the rank of lieutenant. He returned to his home turf to run for sheriff in 2010 and was elected to a four-year term, winning re-election in 2014. With an annual salary of $123,000, he was the second-highest-paid county official.

Jacobson, a crime analyst in the sheriff’s office, had been working there for four years when Duncan called her into his office in late October. She said in an interview with the Star Tribune that she was stunned when he handed her a purported letter.

Jacobson said it spelled out detailed instructions for the two to attend a professional conference in Bemidji in mid-November. They were to book a single room with a king-size bed at the Country Inn & Suites and bring swimsuits and a deck of cards.

The letter laid out a precise route to follow, ordering the pair to travel in the same vehicle. It was one of six purported letters the sheriff told her he had received, Jacobson said.

“I don’t want to hurt your families so don’t make me do it,” one letter said. “I can assure you that if you carry this out without no one knowing your families will be safe and no one will know you did it but you two. If you carry this out, you will never hear from me again.”

‘This is no idol threat’

In another letter addressed to Jacobson, a mother of four, “Control Freak” wrote, “This is no idol [sic] threat. I also know where your kids go to school.”

A letter addressed to Duncan threatened his wife.

“I am sure you don’t want anything to go wrong with her,” it said. “I really don’t think she can defend herself. Just saying.”

In the days after showing Jacobson the letters, Duncan sent her e-mails and texts, discussing how they should respond. Using his personal e-mail address, the sheriff argued that it would be best to follow the orders. He said he believed the letter writer wanted to control them.

“I see no other option here,” Duncan wrote Jacobson. “I look at it this way, if we do it and he keeps his promise then we saved our families. ...

“At least by doing it we have a chance. I think this guy is crazy enough to carry it out but does not want to.”

Jacobson told the Star Tribune that in their first meeting, the sheriff told her that he did not want to involve law enforcement in the case. His refusal to let police investigate made her suspicious, she said. Duncan also said he didn’t plan to tell his wife about the threat against her personally.

Duncan never showed Jacobson most of the purported letters, she said, but claimed to have retyped them exactly as they were written.

Duncan never asked her directly to sleep with him, Jacobson said, but he kept prodding her, asking how far she was willing to go to protect her family. In one text to Jacobson, he wrote, “My thoughts are we have to do it, but only if we are prepared to do what it takes.”

Eight days after Duncan showed Jacobson the first purported letter, she told him she would not go to Bemidji with him. “I said, ‘I will take my chances,’ ” she said. “I’m not going to compromise what I believe.”

Stress took a toll

Jacobson said Duncan had never made any inappropriate advances to her, either verbally or physically, which made the whole situation more shocking. She began applying for other jobs in law enforcement so she could leave the Chisago County Sheriff’s Office.

“I wasn’t handling it very well,” she said. “I would come home and cry. I took days off. I would kind of listen and hear what the sheriff’s schedule would be, and if he was going to be there I would take a couple of days off.”

Finally, at the end of February, she’d had enough. She said she confided in a trusted supervisor, who went with her to the county human resources office, where she made a complaint. The county attorney hired an outside law firm to investigate. Jacobson was placed on family leave, so that any questions about her absence could be refused under federal health privacy laws.

She eventually found a new job in the financial industry.

Chisago County Sheriff Brandon Thyen said Friday that he was “saddened and disappointed” by the information contained in the investigative report. He said the actions outlined were “not only wrong, they run counter to everything our organization and our employees stand for.”

Thyen said his office takes the matter seriously and will continue to cooperate with any ongoing investigation.