He was one of the most beloved teachers in the small world of international schools that serve the children of diplomats, well-off American expatriates and local elites. He was often the first to arrive in the morning, and the last to leave each day. He led students on class trips to exotic places, treating them to cookies and milk at bedtime.
That was the public persona of William Vahey, carefully crafted over four decades until a maid cleaning his home in Nicaragua stole a 16-gigabyte memory drive. There, in photograph after photograph, was evidence that the model teacher had molested scores of adolescent boys, possibly more, in a career spanning 10 schools on four continents.
The discovery of a man the FBI regards as one of the most prolific pedophiles in memory has set off a crisis in the close-knit community of international schools, where horrified parents are being told their children may have been victims of a favourite teacher, and administrators are scurrying to close teacher-vetting loopholes revealed by Vahey's abuses.
"With the sheer volume, the sheer number of incidents in which this man molested, it surprises me that somehow this was not picked up by someone," said John Magagna, the founding director of Search Associates, the world's largest international school recruiting firm. "I don't know what went wrong."
Apparently not even Vahey's victims knew they had been molested. The double-cream Oreos that he handed out at bedtime on the overnight trips were laced with sleeping pills — enough to leave the boys unconscious as he touched them, and posed them for lewd photographs.
Vahey, a 64-year-old native of West Point, New York, attempted suicide in Nicaragua after his maid stole the drive. He survived, but killed himself on a second try, stabbing himself to death in Minnesota on March 21 and leaving hundreds of former students wondering if they were abused.
The agonized father of a student in Caracas, Venezuela, said his son, like many others, would rather not find out, but the boy cannot forget one fact. "He ate the cookies, too," said the father, who spoke on condition of anonymity to protect his son's identity. "Everyone on those trips did."
There were decades of missed opportunities to expose Vahey. An early California sex-abuse conviction didn't prevent him taking a series of jobs working with children. Colleagues and supervisors failed to question why he was so often with boys overnight. And at least twice, boys fell mysteriously ill while under his care and there was no investigation into Vahey's role.
In 1969, Vahey, the son of a decorated World War II pilot, 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 high school where he gave swimming lessons.
Vahey, then 20, told authorities he had started touching boys without their consent at age 14, when he fondled a sleeping teen on a Boy Scout camping trip. He said he touched the genitals or anuses of sleeping boys four more times before the arrest.
The psychiatrist diagnosed Vahey with an "inadequate personality," but added that the disorder did not predispose him to sexual offences dangerous to others. The court even allowed Vahey to start work as a public school teacher's aide after his arrest.
Vahey pleaded guilty to a single charge of lewd and lascivious behaviour. He received a 90-day jail sentence and five years' probation, with a condition that he should be supervised in the company of males younger than 16 during that time. After two years on probation, he was allowed to leave the country unsupervised following college graduation in 1972.
Such leniency was common at the time, said Dan Scott, a retired detective sergeant who worked for 26 years with the Los Angeles Sheriff's Department office that investigates child abuse. "Nobody went after sex offenders."
Vahey was required to register as a sex offender and update his address whenever he moved, but he never updated his information after the first time he registered and authorities didn't pursue the matter. When the state registry was put online in 2004, his name wasn't included because authorities discovered he was no longer living in California.
Vahey began his international teaching career with a year at the American School in Tehran in the run-up to Iran's oil boom, 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 again, Greece and then 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 woman who became a widely respected administrator in international education. He taught eighth- and ninth-grade social studies, coached boys' basketball and led school trips to Bahrain, Turkey and Africa.
Halfway through his 12-year stay in Saudi Arabia, he received a principal's certificate in New Jersey. It was March 1986, seven months before a law took effect requiring all new teachers and administrators to undergo background checks. New Jersey Education Department spokesman Mike Yaple said there is no record of Vahey undergoing a check before he got the certificate.
At least 60 of the 90 or so children in the images were from the Southbank school, according to police, where a significant number of parents said they did not want to know if their children were abused. Woodhead, the governor, has blamed the U.S. system.
"How did he qualify as a teacher in the United States, how is it this information was never available to any of the schools across the world who employed him over the next 40 years?" he asked in an interview with the Press Association.