A former Washington County sheriff's deputy fired after coercing a co-worker into continuing a sexual relationship was arrested and charged with several crimes Sunday, the sheriff's office said.

Jonathan Christensen, a former corporal, turned himself into the Washington County Jail Sunday and was booked on coercion and other charges, according to a news release.

A Washington County grand jury on Friday indicted Christensen on charges of coercion, four counts of official misconduct, domestic assault and domestic strangulation following an investigation that began in April after the sheriff's office received an anonymous email alleging that Christensen and others had engaged in misconduct.

The email also was sent to The Oregonian/OregonLive.

The Portland Police Bureau recently concluded an investigation and the Multnomah County District Attorney's office subsequently presented the case to a grand jury.

Sheriff Pat Garrett fired Christensen, a 16-year veteran of the sheriff's department, in August after finding he likely choked a fellow deputy while in uniform and coerced her into continuing their sexual relationship. His actions violated domestic violence laws and the office code of ethics, Garrett said.

The sheriff had earlier put Christensen on leave after receiving an unsigned letter accusing him and other deputies of having on-duty sex on duty and alleging widespread sexual harassment of female employees.

In an April 29 restraining order petition, the fellow deputy wrote that she told Christensen, who is married to a Hillsboro detective, that she wanted to end their relationship. On March 10, she said, Christensen arrived at her home while he was on duty, wearing his uniform and gun, and shoved her against the wall, pulled her hair and choked her.

The court extended the restraining order in June, finding that Christensen posed a "credible threat" to the deputy.

The order also banned Christensen from the sheriff's office and from having guns and ammunition.

Two other deputies were placed on leave after the agency received the letter. One of them, Sgt. Dan Cardinal, resigned while under investigation in May. The third deputy remains on leave - sheriff's officials have declined to name him.

"While there is a presumption of innocence in our justice system, the allegations against Mr. Christensen are very serious," Garrett said in a statement. "The grand jury's decision is an important reminder that no one, including a law enforcement officer, is above the law."

-- George Rede

grede@oregonian.com

503-294-4004

@georgerede