(CNN) -- A former southern California schoolteacher is set to be arraigned Tuesday amid allegations he bound young students, then photographed them with semen-filled spoons held at their mouths and three-inch cockroaches crawling across their faces, among other graphic depictions.
Authorities have said they have discovered roughly 600 images taken by Mark Berndt, 61, in his classroom.
Dismissed by the Los Angeles Unified School District school board about a year ago, Berndt was arrested January 30. He appeared in court two days later, after which he was ordered held on $23 million bail -- $1 million for each of the 23 counts of lewd acts on a child that he faces.
All of those initial 23 victims were between 7 and 10 years old, and all but two of them were girls, the Los Angeles County District Attorney's Office said.
Berndt has not yet entered a plea.
Since his initial appearance, Los Angeles County Sheriff's Department spokesman Sgt. Dan Scott said an additional 200 photographs purportedly taken by the longtime Miramonte Elementary School teacher had been found.
It is uncertain what, if any, additional charges Berndt may face as a result of that discovery or other developments in the investigation.
The law enforcement probe began when investigators found "over 40 photographs depicting children in a school classroom, with their eyes blindfolded and mouths covered with tape," a Los Angeles County 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," according to the sheriff's department.
Some photos showed "children with large live Madagascar-type cockroaches on their faces and mouths." Others 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," said the sheriff's department.
Scott said that Berndt was arrested soon after lab testing matched Berndt's DNA with a substance -- later determined to be semen -- from a blue plastic spoon and an empty container from a trash bin in his classroom.
The young students "didn't realize they were victimized," said the sheriff's department spokesman.
"They thought they were being blindfolded and gagged as a game," Scott added. "And they were rewarded with cookies or spoons full of sugar, (but) they did not realize the spoon contained semen."
A search of Berndt's home found hundreds of photographs depicting children and a video showing sexual "bondage" activity that "mirrored the bondage-type photos of the children," investigators said.
Parent Bessy Garcia, the mother of two children who were among Berndt's alleged victims, spoke of betrayal.
"He wasn't only a teacher, he was our personal friend," she told CNN earlier this month. "He tricked us. We thought he was the best person in the world."
Los Angeles School Superintendent John Deasy said that Berndt was removed from his teaching job in January 2011, after school officials learned of the police investigation.
A teacher for 30 years, Berndt initially challenged the school district's decision to dismiss him. But he eventually dropped his appeal and resigned last spring.
His arrest this January precipitated a broader fallout, into the adequacy of safeguards for the school's students and the prospect of more victims.
Days after Berndt was taken into custody, another Miramonte Elementary teacher -- Martin Springer, 49 -- was arrested and charged with three felony counts of lewd acts with a girl under the age of 14. He has pleaded not guilty.
The school board subsequently shut Miramonte down for two days, during which the board reconstituted the entire staff in the 1,400-student school. Miramonte is located in unincorporated Los Angeles County within the Florence-Firestone area, about 6 miles south of downtown Los Angeles.