LOS ANGELES (AP) -- A Los Angeles elementary school teacher was charged with committing lewd acts against nearly two dozen students after a film processor gave authorities bondage-style photographs showing children in blindfolds with their mouths taped, and some with giant cockroaches on their faces, authorities said Tuesday.

Mark Berndt, 61, was arrested Monday at his Torrance home and remained jailed on $2.3 million bail, according to a Los Angeles County Sheriff's Department statement.

The charges involve 23 boys and girls ages 6 to 10 between 2008 and 2010.

The investigation started when the film processor gave authorities some 40 photographs depicting blindfolded children in a classroom with their mouths taped shut.

Berndt worked for more than 30 years at Miramonte Elementary School in an unincorporated area of South Los Angeles before being fired as a result of the investigation. Miramonte serves a poor, mainly Hispanic neighborhood. More than half of its approximately 1,400 students are still learning English, according to the school's website.

Some of the photos showed Berndt with his arm around children or with his hand over their mouth.

Other pictures depicted girls with what appears to be a spoon up to their mouths as if they were going to ingest a clear-white liquid.

Sheriff's Lt. Carlos Marquez of the Special Victims Bureau said it was determined the children were given semen on a spoon or on a cookie. A blue plastic spoon and container found in trash in Berndt's classroom tested positive for semen, the sheriff's statement said.

None of the photos showed the students actually eating the semen, but Marquez said the children reported they didn't like the taste.

Authorities are recommending the children be tested for sexually transmitted diseases.

Some of the children's mouths and faces had large, live Madagascar-type cockroaches on them, according to the statement.

The incidents occurred during school hours but not all the children were students of Berndt, Marquez said.

None of the alleged victims told anyone about the incidents and photos, Marquez said.

"They didn't know they were being violated in that manner. They just thought it was a game," Marquez said.

The lieutenant said Berndt was placed under surveillance and it's believed he had no contact with children during the investigation.

Berndt is unmarried, has no children and there's no indication of a previous arrest record, authorities said.

"I am sickened and horrified by the behavior of Mark Berndt," Los Angeles Unified School District Superintendent John Deasy said in a statement.

The teacher was immediately removed when the Sheriff's Department informed the district, and he was fired, Deasy said.

More than 80 current and former students and school employees were interviewed for the investigation.

Searches of the classroom and Berndt's home turned up about 390 photographs depicting children, and at least 10 youngsters in them have not yet been identified, Marquez said.

In addition, A DVD depicting adult sexual bondage activity "which mirrored the bondage-type photos of the children" was also found during the search, the department said, noting that the adults in that video were not identified and those images are not a crime.

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