A Wisconsin high school teacher facing federal child pornography charges in his home state has been charged with allegedly hiding cameras inside hotel rooms while chaperoning students on a trip to Minneapolis last year.

David Kruchten, 37, of Cottage Grove, Wis., was charged Wednesday in Hennepin County District Court with three counts of interfering with privacy.

Authorities allege that he hid cameras in two air freshener cans and a smoke detector in three bathrooms at the downtown Hyatt Regency at 1300 Nicollet Mall.

"All devices were oriented to face toward the toilet and shower area," the charges said. "One of the victims noticed an air freshener on her bathroom counter and went to press a button … the device opened up to reveal the inner workings of a surveillance camera and other related electronics."

The victims were girls between ages 15 and 17.

Kruchten is a business teacher and an adviser for the DECA club, a business-related extracurricular activity, at Madison East High School, said Tim LeMonds, a spokesman for the Madison Metropolitan School District.

He was also an assistant coach for girls' tennis.

Kruchten and a second adult adviser chaperoned students in Minneapolis for a DECA-related event.

According to the charges in Hennepin County: Minneapolis police were called to the Hyatt on Dec. 8 and were told that surveillance devices were found in three rooms.

A man matching Kruchten's description had told a cleaning staffer on Dec. 7 not to clean the rooms where the devices were found. The victims found the devices that night.

Hotel security found that someone made multiple failed attempts to access the rooms using key cards that had been issued to the group, the charges said.

Security also discovered that a room key assigned to the advisers was used to enter the rooms, "showing that the suspect had possession of numerous keys, but was unaware which key belonged to which room and scanned them, in succession, until successfully finding the correct key to gain entry."

Kruchten allegedly told police that students alerted him to the devices and that he delivered two air freshener cans to the lobby on Dec. 8. Police were not called at the time.

Parents called the hotel the same day and said "several" surveillance cameras were found in the students' rooms.

Kruchten also told police he removed thermostats from the walls in the victims' rooms.

Kruchten allegedly told police he gave the thermostats, smoke detector and "other perceived suspicious items" to a security guard. Hotel security reported no such exchange.

Students told police they gave Kruchten the suspicious items on Dec. 7 and that he told the students around 11:30 p.m. to 12 a.m. that he would give them to security.

Surveillance video captured Kruchten walking outside of the hotel and then arriving in the lobby with the air fresheners at 1:35 a.m. Dec. 8.

"The remaining devices found in the rooms of the juveniles were never located," the complaint said. "The defendant had ample time outside to conceal or destroy the items."

Investigators searched Kruchten's phone and found he had an account with a company that sold cameras built to look like air fresheners, smoke detectors and thermostats, according to the complaint.

"These items were consistent with the devices described by the victims," the charges said.

Kruchten is in custody in Wisconsin.

A federal indictment unsealed in Wisconsin last week charges Kruchten with attempting to produce child pornography in two other cases.

Kruchten, who was hired by the school district in 2010, is on paid administrative leave.

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