Updated

The FBI is asking for help to identify at least 90 victims of a suspected serial child predator who worked in American schools worldwide for four decades.

The suspect, 64-year-old William James Vahey, killed himself in Luverne, Minn., on March 21.

FBI agents in Houston filed for a warrant March 19 to search a computer thumb drive that belonged to Vahey, a U.S. citizen. An employee of an American school in Nicaragua where Vahey had recently taught ninth-grade world history and geography gave the drive to the agency.

Special Agent Shauna Dunlap says the thumb drive contains pornographic images of at least 90 boys, aged 12-14, who agents suspect were Vahey's students starting in 2008.

The FBI says Vahey told a Nicaragua school administrator that he drugged his victims.