A woman who received threatening letters written by former Chisago County Sheriff Rick Duncan under the pen name “Control Freak” sued Duncan and the county Wednesday, alleging he intended to coerce her into a sexual relationship while she worked for him.

In a lawsuit filed in U.S. District Court in Minneapolis, Michelle Jacobson, who worked as a crime analyst in the sheriff’s office, alleges that Duncan sexually harassed her, inflicting extreme emotional distress, and that his actions violated her constitutional rights of equal protection.

Jacobson’s suit further alleges that Chisago County created a hostile working environment in violation of the Minnesota Human Rights Act and was complicit in Duncan’s infliction of distress.

Duncan, a former Minneapolis police lieutenant, had served eight years as sheriff when he resigned unexpectedly in May, citing medical issues. With a salary of $123,000 a year, he was the second-highest-paid county official.

Soon after, documents from an independent legal investigation revealed that Duncan had admitted writing threatening letters to Jacobson last fall under the name “Control Freak,” directing her to go with him to a training session in Bemidji and stay overnight at a hotel together or risk harm to her family.

Duncan claimed to have received six letters from “Control Freak.” In one 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.” Another letter addressed to Duncan threatened his wife.

Duncan’s attorney, Marshall Tanick, said Duncan is cooperating with authorities.

“There are a number of disputed and unresolved issues in this case, and we are working with the authorities to try to address and resolve them,” Tanick said Wednesday.

Chisago County Attorney Janet Reiter said the county would not comment on pending litigation.

The county referred Duncan’s case to Anoka County for a criminal investigation. That investigation is still underway, a spokesperson for the Anoka County Attorney’s Office said Wednesday.

Leslie Lienemann, Jacobson’s attorney, said Jacobson would not comment on the lawsuit but wants the issues resolved.

“I think that my client would like to move this case forward, and this is the only way available for her to do that,” Lienemann said.

In a June interview with the Star Tribune, Jacobson called the experience with Duncan “bizarre.”

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

After reporting Duncan’s actions to Chisago County human resource officials, Jacobson resigned from her job with the sheriff’s office.

Jacobson seeks unspecified damages for loss of career opportunity, benefits and future compensation. She also seeks to recover the costs of moving her family to another county “to avoid the presence and influence” of Duncan, as well as compensation for emotional anguish.

Under the state Human Rights Act, any damages awarded could be trebled.