The 13-year-old boy sat in his bedroom, eyes fixed on a computer screen. Justin Berry had hooked up a web camera to his computer, hoping to use it to meet other teenagers online. Instead, he heard only from men who chatted with him by instant message as they watched his image on the internet. To Justin they seemed like friends, ready with compliments and always offering gifts.

Now, on an afternoon in 2000, one member of his audience sent a proposal: he would pay Justin $50 (£28) to sit bare-chested in front of his webcam for three minutes. The man helped him to open an online payment account. “I thought, I took off my shirt at the pool for nothing,” Justin says. “So, I was kind of like, what’s the difference?”

Justin removed his T-shirt. The men watching him oozed compliments. So began the secret life of a teenager who, over five years, sold images of his body on the internet. From the seduction that began that day, he was drawn into performing in front of the webcam — undressing, taking a shower, masturbating and even having sex — for an audience of more than 1,500 people who paid him, over the years, hundreds of thousands of dollars.

Justin’s story sheds light on the dark side of the internet. Minors, often under the online tutelage of adults, are opening paid-for pornography sites featuring their own images captured for the internet by inexpensive webcams. They perform from the privacy of home, while parents are near by, beyond their children’s closed bedroom doors. The business has created youthful internet pornography stars with nicknames such as Riotboyy, Miss Honey and Gigglez, whose images are traded online long after their sites have vanished. In this world, adolescents announce schedules of their next masturbation for customers who pay. Customers can even buy private shows in which teenagers sexually perform while following real-time instructions.

A six-month investigation by The New York Times found that such sites have emerged largely without attracting the attention of the police or youth protection organisations in the US. “We’ve been aware of the use of the webcam and its potential use by exploiters,” says Ernest E. Allen, chief executive of the National Centre for Missing and Exploited Children. “But this is a variation on a theme that we haven’t seen. It’s unbelievable.”

In this virtual universe, adults hunt for children on legitimate sites used by young webcam owners who post contact information in the hope of attracting friends. If children respond to messages, adults groom them — with praise, attention and gifts — before trying to persuade them to film themselves pornographically. The lure is the prospect of easy money. Many teenagers solicit donations, request gifts through sites such as Amazon or negotiate payments, while a smaller number charge monthly fees. But there are other beneficiaries — including businesses (some unwittingly, some intentionally) that provide services such as web hosting and payment processing.

Not all victims profit: some children end up as pornographic commodities. Adolescents have appeared naked on their webcams as a joke, or as presents for boyfriends or girlfriends, only to have their images posted on paid-for pornography sites. One website boasts that it features 140,000 images of “adolescents in cute panties exposing themselves on their teen webcams”.

The scale of webcam child pornography is unknown because it is new and secretive. One online portal that advertises paid-for webcam sites, many of them pornographic, lists at least 585 sites created by teenagers. At one computer bulletin board for adults attracted to adolescents, a review found webcam image postings of at least 98 minors in one week.

The New York Times inquiry has already resulted in a criminal investigation. In June the newspaper found Justin Berry, then 18, who revealed the existence of a group of more than 1,500 men who paid for his online images, as well as evidence that other identifiable children as young as 13 were being exploited. The paper persuaded Justin to abandon his business and helped him to contact the US Justice Department. Arrests and indictments of adults he identified as pornography producers and traffickers began in September. Investigators are also focusing on businesses, including credit card processors, that have aided illegal sites. Anyone who has created, distributed, marketed, possessed or paid to view such pornography is open to a criminal charge. ()

Child pornography in America was once a small trade relegated to back rooms. But as internet use boomed in the 1990s paedophiles found ways to meet online and swap illegal photos. They began to fantasise about the day when they would be able to reach out to children directly, through instant messaging and live video, to obtain the pornography they desired. Their dream was realised with the web camera, which by 2000 was commonly used by computer-aware young people.

Among them was Justin Berry. That year, he was a gangly 13-year-old with saucer eyes and brown hair that he often dyed blond. He lived with his mother, stepfather and younger sister in Bakersfield, California, 90 miles north of Los Angeles.

Already he was so adept at the computer that he had registered his own small website development business, which he ran from the desk where he did his school homework.

“I didn’t have a lot of friends,” he recalls, “and I thought having a webcam might help me to make some new ones online, maybe even meet some girls my age.”