The discovery that Neil Havens Rodreick had managed to dupe the authorities at several schools into believing he was a school age child by shaving off his body hair and dressing as a child has shocked Arizona, and much of America.

"Everyone who hears about this is shocked. It's a bizarre twist that a 29-year-old man would pose successfully four times as a 12-year-old and would try to gain access to children in charter schools," said Rebecca Ruffner, the director of Prevent Child Abuse Arizona, a children's advocacy group. "This is a completely new threat to our children."

Yesterday, authorities from several counties of Arizona as well as Oklahoma, where Rodreick was jailed as a sex offender in 1996, were meeting to try to unravel the last few years of his life. So far, he and the three other men face 25 charges each, ranging from fraud and forgery to child molestation. But there could be more charges, Susan Quayle, a spokeswoman for the Yavapai county sheriff's office, said.

There is no evidence to date that Rodreick harmed any of the children at the schools where he was enrolled. However, he is under investigation in a number of jurisdictions for failing to register as a sex offender, and for keeping large caches of child pornography on his computer. The authorities also have a video showing him having sex with a boy.

Rodreick's deception on the Arizona schools sytem appears to have been an elaborate scam, worked in concert with three other men. Two of the men living with Rodreick - Robert James Snow, 44, and Lonnie Eugen Stiffler, 61 - had posed as his guardians. They too were Rodreick's dupes, believing that he was 12 years old after meeting on the internet where they were trawling for boys. By 2004, Stiffler was wiring Rodreick money. By 2005, the authorities say, Rodreick persuaded the men to meet him at an Oklahoma hotel, and take him to Arizona, where Stiffler posed as his grandfather and Snow an uncle. The fourth man in the ring, Brian Jay Nellis, 34, had been Rodreick's cellmate in an Oklahoma prison after he was convicted of making indecent proposals to two six-year-old boys. Nellis was also serving time for child sex offences. All but Stiffler had previous convictions as sex offenders.

So far, their masquerade is known to stretch back at least to August 2005 when Rodreick enrolled at a charter school in Gila County, Arizona. That school, like all the others he targeted, belongs to a system of publicly funded independent schools that may have been selected, investigators believe, because they have lesser oversight than public schools.

Rodreick was enrolled in Gila County for 21 days, and attended for only a few days before he was withdrawn. Next he moved to the town of Surprise, a suburb of Phoenix. "He absolutely looked age-appropriate," Rhonda Cagle, a spokeswoman for Imagine Charter School, told the New York Times. "He took all of the subjects our students take - math, social studies," she said. "By all accounts from the teachers, he was fairly quiet and withdrawn. He turned in homework, certainly didn't come off as brilliant or as someone needing extra help."

Rodreick's ruse was eventually detected on January 17 when he attempted to enrol at the Mingus Springs charter school in Chino Valley, a middle school with fewer than 200 students. At first, Rodreick tried to explain away his missing records by saying he had been schooled at home, said Chris Igel, the school board president. But the school grew suspicious of the paperwork that Rodreick did present.

When the authorities faxed the documents to the issuing authorities, they discovered they were forgeries and telephoned the police.

"The school office folks did notice that he seemed older, but the age that everybody guessed was 16," Mr Igel said. "The big thing here is we thought he was an abducted child. There is not a word in the English dictionary to describe the reaction that everyone has had on this."