Los Angeles school officials are trying to determine how a former elementary school teacher charged with molesting 23 children over a two-year period and taking photos of them could have committed the crimes, possibly in a school classroom, without anybody finding out.

“We are trying to understand, how could that have happened?” said Los Angeles Unified School District Superintendent John Deasy in a phone interview with msnbc.com. “We’ve had no complaints from parents or students.”

Authorities arrested Mark Berndt, 61, Monday at his Torrance home following a year-long probe that began when a film processor turned in the images to law enforcement. Berndt had been a teacher at Miramonte Elementary School in an unincorporated area of south Los Angeles for more than 30 years, but was fired by the school district shortly after the investigation began in January 2011.

Deasy said there was nothing in Berndt’s long record with the school district to indicate a problem. “Not so much as a single complaint,” he said.

"I am disgusted beyond belief,"  Deasy said. "I'm a dad as well as a superintendent and it's horrifying." 

Cockroaches on their mouths
Some of the images allegedly show Berndt with his arm around the children or with his hand over their mouths, according to a statement by the Los Angeles County Sheriff's Department. In addition, authorities say the images depict girls with a blue plastic spoon filled with a substance, later determined to be semen. There were also photos of children with large, live Madagascar-type cockroaches on their faces and mouths.

Early in the investigation, Special Victims Bureau detectives recovered a blue plastic spoon and an empty container from the trash in the suspect's classroom. The recovered items tested positive for semen, authorities said, and the suspect's DNA matched the DNA profile found on the spoon and container.

"We ended up finding out through DNA that the white substance was bodily fluids from our suspect," Lt. Carlos Marquez told NBCLosAngeles.com. A search warrant served by detectives on Berndt's home also led to the discovery of more than 100 similar photographs depicting children, authorities aid. Also found was a DVD depicting adult sexual "bondage" activity. The adults in that DVD are not identified, according to detectives.

Vicims were ages 6-10
As part of the investigation, authorities say they have interviewed more than 80 current and former students, as well as school employees. The victims are identified as 23 boys and girls between the ages of 6 and 10, during a time period from 2008 to 2010.

Investigators are still working to identify 10 of the child victims in the 390 photos uncovered.

Authorities are recommending the children be tested for sexually transmitted diseases, the Associated Press reported.

Berndt was being held Tuesday on a $2.3 million bail. Berndt is unmarried, has no children and there's no indication of a previous arrest record, authorities told the Associated Press.

Investigators are seeking help from the public to identify possible additional victims during the suspect's tenure at Miramonte Elementary School.

Deasy said "crisis counseling and support have been provided for more than a year to the known victims and their families, and we continue to offer those necessary services to new victims as they are identified or any student or parents who requests assistance."

He said the district is reviewing its policies to ensure that classrooms that appear empty at the end of the day, are truly vacant. Besides having a crisis team at the elementary school, Deasy said the district is also reaching out to the middle school and is planning community meetings to discuss parent concerns. 

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