Story highlights The young students "didn't realize they were victimized," an investigator says

Children were told they were playing a game, may have been spoon-fed semen

In classroom photos, students had "eyes blindfolded and mouths covered," officials say

Mark Berndt, a 30-year teaching vet, is charged with child molestation

A Los Angeles elementary school teacher allegedly took bondage photos of more than two dozen students in his classroom, including some with suspected semen-filled spoons at their mouths, investigators said Tuesday.

The young students "didn't realize they were victimized," Los Angeles County Sheriff's Sgt. Dan Scott told CNN Tuesday.

"They thought they were being blindfolded and gagged as a game," he said. "And they were rewarded with cookies or spoons full of sugar (but) they did not realize the spoon contained semen."

The photographs also showed "a large 3-inch cockroach that would crawl on their face," Scott said.

Mark Berndt, 61, was arrested on child molestation charges at his Torrance, California, home Monday and is being held pending $2.3 million bond in a Los Angeles County jail, according to Sheriff's Lt. Carlos Marquez.

He is scheduled to make a first appearance before a judge Wednesday morning on 23 counts of lewd acts on a child, according to the county's district attorney.

CNN was not able to immediately identify or reach Berndt's lawyer.

While the investigation began more than a year ago, the arrest came soon after lab testing matched Berndt's DNA with semen found on a spoon recovered from his classroom, Scott said. Investigators persuaded the suspect to voluntarily give them a DNA sample just two months ago, he said.

The 30-year teaching veteran was removed from his job at Miramonte Elementary School in south Los Angeles on January 7, 2011, the day the sheriff's department told the school district about the investigation, Los Angeles School Superintendent John Deasy said.

"I am sickened and horrified by the behavior of Mark Berndt. This individual and his conduct do not reflect on the quality of the teachers who work so hard on behalf of the students in the Los Angeles Unified School District," Deasy said in a written statement.

The probe started when a film processor gave investigators "over 40 photographs depicting children in a school classroom, with their eyes blindfolded and mouths covered with tape," the sheriff's statement said.

"Investigators learned that some of the photos depicted suspect Mark Berndt with his arm around the children, or with his hand over their mouths," it said.

Some photos show female students with "what appeared to be a blue plastic spoon, filled with an unknown clear/white liquid substance, up to their mouths as if they were going to ingest the substance," the statement said.

Other photos showed "children with large live Madagascar-type cockroaches on their faces and mouths," it said.

Investigators, who interviewed more than 80 current and former students and school employees, identified 23 boys and girls then between the ages of 7 and 10 years old as victims in crimes that are believed to have been committed between 2005 and 2010, it said.

A search of Berndt's home found more than 100 more similar photographs depicting children and a video depicting adult sexual "bondage" activity "which mirrored the bondage-type photos of the children," investigators said.

The film processor later gave investigators an additional 250 photographs, it said.

About 10 children seen in the more than 400 images have not yet been identified, it said.

"Early in the investigation, Special Victims Bureau detectives recovered a blue plastic spoon and an empty container from the trash within the suspect's classroom," the sheriff's statement said. "The recovered items tested positive for semen. Through further investigation, the suspect's DNA was obtained and tested, and (investigators) determined that it matched that of the DNA profile found on the spoon and container."

Investigators did not reveal the contents of the fluid to the children or tell them that the case involved child molestation allegations, Scott said.