The FBI is hastily seeking to identify victims of a serial pedophile who drugged and molested dozens of children over four decades teaching at international schools around the world.
William James Vahey, 64, took his own life in March in a Minnesota hotel room while the subject of an international sex crimes probe covering his teaching in nine countries, the Federal Bureau of Investigation said.
The agency said it obtained a thumb drive belonging to the American which contained catalogued and dated pornographic images depicting at least 90 boys approximately 12 to 14 years old.
"When Vahey was confronted about the images, he reportedly admitted molesting boys throughout his entire life and said he gave the minors sleeping pills prior to the molestation," the FBI said in an alert.
Vahey taught overseas from 1972 until days before his death including at private academies that served children of American diplomats and military personnel, as well as locals, according to the FBI.
He had a 1969 conviction for child molestation in California.
"I've never seen another case where an individual may have molested this many children over such a long period of time," Special Agent Patrick Fransen said.
The seized images dated back to 2008, but Fransen feared Vahey may have preyed on "many other students" - American and international - before that.
Vahey's teaching assignments included a 1992-2002 stint at Indonesia's prestigious Jakarta International School, where the nursery was ordered closed this week following allegations a six-year-old boy was sexually abused by cleaning staff in the toilets.
He spent a dozen years at Saudi Aramco Schools in Saudi Arabia, as well as two separate teaching stints in Iran in the 1970s. His last assignment was at the American Nicaraguan School in Managua, where his employer saw the thumb drive.
Vahey, who taught history, geography and social studies, also worked at schools in Britain, Greece, Lebanon, Spain and Venezuela.
He also served as basketball coach for the schools' boys teams and regularly accompanied them on overnight trips.
"He had access to children because of his position of trust," Fransen said. "He created a system that gave him the opportunity and the means to molest children."
The FBI said the photographed victims were being identified and notified, and the agency was working on the investigation with international partners.
It also appealed for help in locating other potential victims, and encouraged them to contact the FBI or the nearest US embassy.