Luke De Roy Krieger, a civilian employee with the Washington County Sheriff’s Office, is accused of distributing child pornography online while at work and enticing a minor online for sex in a case that was initiated by British police.

Krieger, 39, an information systems analyst, made his first appearance Wednesday in federal court in Portland after his arrest the day before. His court-appointed lawyer, Bryan Francesconi, entered not guilty pleas to the allegations on Krieger’s behalf.

Krieger was placed on unpaid administrative leave after his arrest.

"The Sheriff’s Office has been fully cooperating with the involved agencies to ensure a thorough investigation,'' Washington County Sheriff Pat Garrett said in a statement. "While our criminal justice system is based on the presumption of innocence, I’m repulsed by the charges.''

In August, undercover investigators from the United Kingdom Police Eastern Regional Special Operations Unit contacted federal agents with U.S.Homeland Security Investigations to help identify a person who had engaged them on a mobile app, expressing his sexual interest in children as young as newborns, according to a federal complaint unsealed Wednesday.

Investigators traced the user’s IP address to Krieger, who lives in Camas, but found it was accessed from a business internet account registered to the Sheriff’s Office in Hillsboro. Further investigation revealed Krieger worked for the office.

In subsequent online chats with undercover officers, Krieger revealed an interest in having sex with children as young as 5 and having sexual fantasies about children he came into contact with regularly, the complaint says. He also shared his desire to use a spy camera to take photos and videos of girls in a state of undress, according to the complaint.

Krieger ended up expressing interest in traveling to Boise to have sex with an undercover officer posing as a 13-year-old girl, Detective Robert Givens of Homeland Security Investigations wrote in the complaint. Krieger sent a nude photo of himself from the neck down to the suspected 13-year-old as well as child pornographic images to the teenager’s purported father, also an undercover officer, the complaint says.

“Based on the times of the chats and statements made during the chats by the subject, I believe that the subject was conducting many of the chats’’ with the undercover child and father “while at work,’’ Givens wrote.

Krieger was arrested Tuesday afternoon before traveling to Idaho. He’s being held at the Multnomah County Detention Center and is due back in court Friday for a detention hearing.

The Sheriff’s Office was notified of the investigation in September. At the request of investigators, the sheriff’s officials kept Krieger on the job until his arrest "to preserve the integrity'' of the investigation, according to the Sheriff’s Office.

Krieger, according to state records, started as a reserve deputy for the Sheriff’s Office in June 2002. He became a corrections deputy in 2004 and was reclassified as a civilian employee in May 2009.

He worked as an analyst for an information technology work group and had no contact with the public and had no enforcement responsibilities, according to the Sheriff’s Office.

-- Maxine Bernstein

Email at mbernstein@oregonian.com

Follow on Twitter @maxoregonian