Prosecutors charge that Rex used his network to recruit teenagers who could help him abduct a small boy. Officials say Rex wanted to sexually abuse the child-and possibly kill and eat him. According to chilling details recorded in court papers, a teenager says that Rex told him that he almost grabbed a child himself at a New Hampshire mall recently when he saw a small boy going into a bathroom alone. Last week Rex pleaded not guilty to various child-abuse and pornography charges; he is being held on $2 million surety bail.

Rex’s case is particularly grisly, but law-enforcement officials from California to Florida say that opportunities for on-line pedophilia are escalating as both kids and pedophiles become more computer literate. “A warning should go out to parents,” says Thomas Reilly, the prosecutor in the Rex case. Pedophiles go where the kids are and, increasingly, the kids-especially the boys-are hooked up to computer networks. Instead of hanging around the playground looking for the loneliest kid, potential child molesters merely have to log on. Many of the victims are latchkey kids, home alone with only a screen for company. Others are youngsters with social problems who feel most comfortable on line where “they can assume any persona they want,” says Fred Cotton of SEARCH, a Sacramento, Calif., group that helps police deal with computer crime. “Now they have a means of communication. But it leaves them very vulnerable.”

Last month police in Cupertino, Calif, arrested Donald Deatherage, a 27-year-old computer engineer who assumed the nom de net HeadShaver on America Online. Police say Deatherage used his computer to prey on a 14-year-old boy. After many online conversations, he persuaded the boy to meet him in person. Then, police say, Deatherage handcuffed, shackled and blindfolded the boy before taking him to his apartment. There, he spanked the boy with a belt, forced him to have an enema, shaved the boy’s legs and pubic hair and had sex with him. After the meeting, police say, Deatherage ordered the boy to write about the abuse. When the boy’s father discovered the graphic account, father and son went to the police. Deatherage wanted to relive the experience by having the victim write it down, police say. Last week he pleaded guilty to two counts of oral copulation and one count of sodomy.

Since then, police in Santa Clara County, where Deatherage lives, say they’ve been overwhelmed by phone calls from bulletinboard users warning them that there are many more Deatherages in cyberspace. They’re checking out the tips. No one actually knows how many pedophiles are on line, although officials say child pornography is readily available on the Internet, the international computer network. Technology has made it easier to disseminate dirty pictures and text. No more magazines in plain wrappers -or raids by postal inspectors. With a modem hooked up to a computer in the privacy of their bedrooms, pedophiles have access to X-rated material from all over the world, including countries where child-porn laws are more lenient. Last year U.S. Customs Service officials seized the computers and discs of 35 Americans who were downloading child pornography in Denmark.

In the battle against electronic pedophiles, the police are technologically outgunned. Most cops don’t know much about computers, says Gary Narzissenfeld, a special agent for the U.S. Customs Service. And investigators trying to learn often labor with inadequate equipment. Government-ordered computers can arrive three years after they are requisitioned. Brian Kennedy, a detective in the Sacramento County Sheriff’s Department in California, says he was unprepared for the 14-year-old boy and his mother who showed up several years ago with a handful of floppy discs containing pornographic materials the boy had received from an adult he met on line. When the boy looked at Kennedy’s computer, he was appalled. His response: “Is this all you’ve got?” Kennedy later got help from IBM to crack the case against the boy’s on-line correspondent.

Although some police departments are setting up special units to deal with computer crime, officials say that at the moment, the best defense against on-fine pedophilia is at home. Too often parents let kids while away hours in their rooms, assuming that nothing more dangerous than Nintendo target shooting is on the screen. Putting the computer in a public area, like the living room, would help. Some commercial services, such as America Online, also have “parental control” options allowing parents to filter out material such as electronic chat, which can be racy. Parents should talk to kids about the dangers of cyberspace. The rule is the same as on the street or in the park: Beware of strangers.