The children at Miramonte Elementary School never complained about their third-grade teacher. Not, authorities said, when he blindfolded them, not when he put tape over their mouths or even placed live cockroaches on their faces.

He told them it was a game and then photographed them, creating images that would eventually lead to his arrest, investigators said of Mark Berndt, who is scheduled to be arraigned Wednesday on charges that he committed lewd acts on 23 boys and girls, ages 6 to 10, between 2008 and 2010. He has hired a lawyer and has made no statements to authorities, said Los Angeles County sheriff's spokesman Steve Whitmore.

The investigation began when a film processor found Berndt's photos more than a year ago. Since the discovery, the school district fired Berndt and police put him under surveillance.

"If it wasn't for the film processor, this could still be continuing today," said sheriff's Lt. Carlos Marquez.

Berndt was arrested Monday at his home in Torrance and was being held on $2.3 million bail.

Some parents picking up their pre-kindergarteners at the school on Tuesday complained that officials at the school in South Los Angeles should have notified them when the photos were found.