Students at a California high school were asked to turn in their yearbooks after a photo was discovered inside the memory book of two students possibly engaged in a sex act, authorities said on Thursday.
San Bernardino County investigators were notified on Tuesday and Big Bear High School employees and detectives began collecting the yearbooks in the mountain community at Big Bear Lake, 70 miles east of Los Angeles.
The background of a school dance photo shows a 17-year-old boy's hand inside the clothing of a 15-year-old girl in a way that suggests sexual penetration.
"The photo was taken at a dance and the suspect and victim are not the focus of the photo. They are in the background and likely didn't know they were in the photo," said sheriff's spokeswoman Cynthia Bachman.
It went unnoticed by the yearbook adviser.
"When the adviser scanned the photo, it was very easy to overlook," Bachman said.
But the scandalous picture didn't escape student notice after the yearbooks were distributed.
"You know, how you look at a photo and don't notice what's in the background? Then, it's, `Oh my gosh, look what's going on back there,'" Bachman said.
Authorities said no one has been arrested but they released no other information on the boy and girl.
Most students have returned the yearbooks for editing, which involves covering the suspect photo with another page or another photograph.
Detectives were contacting students who haven't turned in yearbooks with a warning they could face a charge of possessing child porn.
Telephone calls to the principal's office were referred to the school district. Tim Larson, spokesman for the Bear Valley Unified School District, didn't immediately return a telephone message.
The last day of classes is Friday, according to the school calendar.