Portland Police Sgt. Pete Simpson said Russell Gordon, 44, allegedly concealed the pen camera on his co-worker's desk at the MB&G consulting firm, where he has been employed as IT manager for more than 10 years, KGW-TV, Portland, reported Wednesday.
The woman discovered the camera and turned it in to supervisors.
"Investigators determined that Gordon placed the camera on the victim's desk to capture her use of a breast pump. There's no other suspect but this man, on video quite clearly setting this pen in the area," Simpson said.
Gordon was booked into the Multnomah County Jail on charges of second-degree burglary and invasion of privacy.
"We have all felt victimized. When the trust is gone, we're left shocked," MB&G President Steve Fairweather said.