That was the public persona of William Vahey until a maid stole a memory drive from him in November. It held evidence that Vahey had molested scores of adolescent boys, possibly more during a four-decade teaching career.
"He's one of the most prolific pedophiles that we've seen here due to the sheer numbers," FBI Special Agent Sharon Dunlap said.
The discovery has set off a crisis in the community of international schools, where parents are being told their children may have been victims, and administrators are scurrying to close loopholes exposed by Vahey's abuses.
Apparently, not even Vahey's victims knew they had been molested. The double-cream Oreos that he handed out were laced with sleeping pills - enough to leave the boys unconscious as he touched them and posed them for nude photographs.
Vahey attempted suicide in Nicaragua after his maid stole the drive. He survived, but killed himself on a second try, stabbing himself to death at age 64 and leaving hundreds of former students wondering if they had been abused.
There were decades of missed opportunities to expose Vahey, starting with an early California sex-abuse conviction that didn't prevent him taking a series of jobs exposing him to children.
In 1969, Vahey was arrested on child sexual abuse charges after police said he pinched the penises of eight boys, ages 7 to 9, at an Orange County, California, high school where he taught swimming. Vahey, then 20, told authorities he had started touching boys without their consent at age 14.
He pleaded guilty to a single charge of lewd and lascivious behavior. He received a 90-day jail sentence and five years' probation, but he was allowed to leave the country in January 1972.
Vahey began his international teaching career at the American School in Tehran, the first in a series of stays around the Middle East and Europe. He taught history, social studies and related subjects in Lebanon, Spain, Iran, Greece, Indonesia and Saudi Arabia, almost always to middle school students.
By the time he arrived in Saudi Arabia, Vahey was married and had two sons with Jean Vahey, a widely respected administrator. In addition to teaching, he coached basketball and led school trips to Bahrain, Turkey and Africa.
Authorities may have missed a warning sign during a later teaching stint in Venezuela: Two students under Vahey's care were rushed to a hospital after falling unconscious in their hotel room on a trip, parents and staff said. Officials were unable to determine why and chalked it up to a possible failing air conditioner.
Seven years later, the Vaheys went to work at the Westminster campus of London's Southbank International School, with about 350 pupils from 70 countries. Police say at least 60 of the 90 or so children in the images on the USB drive were from that school.
Southbank's chair of governors, Chris Woodhead, told Britain's Press Association there had been one complaint against Vahey, but, "The boy's parents agreed that there was nothing untoward and the matter shouldn't be pursued," Woodhead said.
In early March, the maid who had taken the memory drive handed it to American Nicaraguan school director Gloria Doll, who found it contained photos of unconscious boys, many between the ages of 12 and 14, often being touched by Vahey.
Doll confronted Vahey, who told her, according to an FBI affidavit, that he had given the boys sleeping pills, adding: "I was molested as a boy, that is why I do this. I have been doing this my whole life."
Vahey said he had swallowed more than 100 sleeping pills in November after discovering the USB drive had been taken.
Doll demanded Vahey's resignation, according to the affidavit, and notified authorities at the U.S. Embassy in Managua the next day, U.S. officials said. Embassy officials immediately notified Nicaraguan police, but Vahey had already flown out of the country.
Vahey traveled to Luverne, Minnesota, where relatives live. He checked into a hotel and stabbed himself in the chest with a knife, leaving a note apologizing to his family.
The discovery has led to reviews of recuiting policies, background checks and security procedures at organizations of schools around the world.
In the meantime, one of the men molested by Vahey in the Westminster, California, swimming pool as a 9-year-old says terrible memories have revived.
"It certainly bothers me that a person like that would be left unsupervised and obviously not tracked over the last 45 years now," the man said, his voice growing unsteady. "I find it troubling. I guess the question is: How can the system allow that to happen?"
Weissenstein reported this story from Mexico City and Abdollah reported from Los Angeles. AP writers Luis Manuel Galeano in Managua, Nicaragua; Adam Schreck in Dubai; Niniek Karmini and Margie Mason in Jakarta; Joshua Goodman in Caracas, Venezuela; Jill Lawless and Sylvia Hui in London; and Carson Walker in Luverne, Minnesota, contributed to this report.