It wasn't a veteran crime detective or a neighborhood watch group or even a suspicious parent who helped put a 61-year-old elementary school teacher with no previous criminal record in jail for allegedly committing lewd acts on nearly two dozen children.
It was one of the anonymous photo processing guys at the neighborhood CVS store where authorities say Mark Berndt dropped off his old-fashioned film to be developed.
Police were called as soon as the film processor saw photos in November 2010 of children blindfolded and their mouths covered in clear tape. The subsequent investigation, which lasted more than a year, resulted in Berndt's arrest earlier this week. He appeared in court Wednesday, where his bail was set at $23 million.
Berndt is charged with committing lewd acts on 23 boys and girls, ages 6 to 10, between 2008 and 2010 at Miramonte Elementary School, where he had taught for more than 30 years. He was fired in January 2011 when school officials learned of the police investigation.
Authorities say that after locking his classroom door, Berndt would tell the children they were playing a game in which they were blindfolded and their mouths taped shut. Other times he would have them take part in a "taste test" in which authorities say he would feed them his sperm after he'd placed it on a cookie or spoon. They say he also put a large cockroach on the faces of some children.
It was his penchant for taking pictures of the "games" that authorities said led to his arrest. It appears no child ever complained about the games, and the pictures show some seemed to enjoy them, authorities said.
But when film with about 40 images was taken to a CVS pharmacy in Redondo Beach, where Berndt lives, a technician who saw the pictures called police, who contacted the Los Angeles County Sheriff's Department.
California is one of nearly a dozen states that require police be called if a photo technician sees any pictures he or she suspects depict child abuse.
The law generates more calls than might be expected, even in the age of the digital camera, said Detective Juan Perez, who investigates child sex crimes for the Los Angeles Police Department.
"People take that stuff to photo places all the time," said Perez, adding that his department's sexually abused children unit investigates several tips a year from photo technicians.
"I couldn't give you a figure off the top of my head but we got several last year," he said.
He said such tips have declined in recent years as use of digital cameras — which don't require film — has become nearly ubiquitous. But at the same time, Perez and other investigators say, tips from photo stores that make prints from CDs, smart cards and flash drives have picked up.
At the Redondo Beach CVS store on Pacific Coast Highway, where sheriff's officials say Berndt took the film to be processed, the self-serve photo kiosks were shut down Wednesday. No technicians were present and all film processing had been canceled. No store employee would discuss Berndt's arrest.
"Due to the ongoing investigation of the photos developed in our Redondo Beach store, we cannot comment on this specific matter," said CVS spokesman Mike DeAngelis.
He added, however, that it is company policy for CVS technicians to alert store managers if they see any photos containing "inappropriate material."
California's Mandatory Child Abuse Reporting Act, adopted in 1980, requires that such reports be made immediately to police and that a full written report, with copies of the photos, be turned over within 36 hours.
Meanwhile, people who run photo labs say it shouldn't surprise anyone that at some point someone will look at their pictures.
"We are not interested at looking into people's privacy. We are only looking at composition," said Alex Yi, who has owned the Kodak One Hour Photo Store in Los Angeles for 23 years.
When photos are scanned or negatives or printed, he and others say, a technician has to look at the image to see if the color is properly balanced and the focus is correct. If not, people aren't going to want to pay for the photo.
At his store, he said, no one shares photos around, not even the ones of naked people they sometimes get. But at least one person sees every photo that comes in.
Over the years Yi has seen his share of nude photos, usually of people and their spouses. He lets those go by, but if they get more explicit, he says, he refuses to print them.
"And the child thing we absolutely have to report it," he said. "Fortunately we have never gotten any. But if we got any I would do the same thing the guy at CVS did."
Associated Press Writer Amy Taxin in Redondo Beach, Calif., contributed to this story.