DALLAS - When federal agents and Euless, Texas, police officers showed up at his door, Tim Whitington didn't even ask why they were there.

"You're here for the bad stuff," he said.

And just like that - after agents escorted a young boy away - Whitington directed them to a wooden box containing a flash drive.

What they found was disturbing: graphic pornographic images of children. Even more troubling was the discovery of a relatively new form of child pornography, one in which perpetrators request a specific type of molestation they watch online as it happens.

The photographic evidence, and Whitington's arrest, led to the apprehension of a half-dozen child molesters across the country.

The Whitington case was a victory in the fight against child pornography, law enforcement officials say. It's a war worth waging, but one they don't expect to win.

In a typical week, the National Center for Missing and Exploited Children in Virginia fields about 10,000 child pornography-related tips, said Michelle Collins, vice president of the center's exploited children division. About 91 million child porn images and videos have been seized by authorities since 2002.

In comparison, the number of child pornography arrests is small: An estimated 5,000 people nationwide were arrested in child porn crimes, such as possession or distribution, in 2009, the latest figures from the Crimes Against Children Research Center at the University of New Hampshire.

The number of arrests for producing child pornography, as in the Whitington case, was less than 2,000 in 2009.

Last week, 255 people were arrested as part of a national roundup of child predators.

It's no secret what's behind the rapid increase in the creation and distribution of child pornography, experts say. The Internet has made child pornography easy to make, find and trade.

Law enforcement groups target the problem, but their numbers are small and the caseload heavy. The topic will be explored next month when experts from around the world come to Dallas for the annual Crimes Against Children Conference, which will be hosted by the Dallas Police Department and the Dallas Children's Advocacy Center.

The public, for the most part, doesn't want to face the problem, said Assistant U.S. Attorney Alex Lewis, who prosecuted Whitington.

"Who wants to think of something as grotesque and awful as children being raped for someone's pleasure?" Lewis asked. "No one wants to believe that it actually lies in the heart of a man."

Authorities say the public needs to be aware of the rarely discussed crime.

Whitington, who declined an interview from prison, was an outwardly unremarkable 44-year-old businessman when he was arrested at his Euless apartment in 2010.

But Pat McGaha, a Homeland Security Investigations agent, called him a "monster" and the people he traded images with "vipers."

Homeland Security Investigations is a division of U.S. Immigration and Customs Enforcement. The department is one of the main agencies that investigates child pornography because so much of the material crosses state and national borders.

Whitington's case, which is still leading to prosecutions almost three years later, offers a rare glimpse into the battle against child porn production.

abuse, plain and simple

Whitington's world began unraveling in November 2010 in Australia. A known sex offender was arrested for possession of "first generation" child pornography - images police had never seen before.

Many pictures seized by authorities have circulated for decades. Some are known by name, such as the "Misty" or "Vicky" series, and are highly prized by child pornography "collectors." For them, it's like collecting baseball cards.

"First generation" material alarms officials because it means there's a new victim.

And make no mistake, said Dan Powers, clinical director of the Children's Advocacy Center of Collin County, northeast of Dallas: Child pornography is abuse. The majority of actively traded images show some sort of physical sexual abuse of pre-pubescent children, according to Powers.

"This is not 'dirty pictures,' " Powers said. "This is victimization of children."

Powers and other experts avoid the term "child pornography" because it minimizes the crime. Children, unlike adults, cannot consent.

"It is not porn," said Matthew Dunn, a cybercrime supervisor in the Irving office of Homeland Security Investigations. "It is child abuse material, plain and simple."

The pictures viewed in Australia were made in England by a man who raped a boy and a girl under the age of 13. After his arrest, officials tipped their American counterparts that the Englishman also had been chatting online with a man known as "Txfordguy."

The information reached the Irving office of Homeland Security on Dec. 23, 2010.

Like everyone else, agent Brad Hudson was ready to shift into holiday mode.

When he read the online chats with "Txfordguy," he knew agents needed to act.

"Txfordguy," also known as "Timdubbya," had told the English molester, "I want you to do x-y-z to your kids and send me those pictures so I can show it to (my victim)," Hudson said.

"What we had was him directing somebody to produce child porn and send it to him," the agent said. And the chats indicated "Txfordguy" planned to rape a boy he knew.

double-edged sword

The Internet is a double-edged sword: It makes sexual abuse images incredibly easy to access but also leaves electronic footprints.

Homeland Security quickly traced the account used by "Txfordguy" to Whitington's apartment. A background check showed he was a divorced father without a criminal record.

"He was just your average Joe, coming to work and going home," Hudson said.

The ordinariness of child porn offenders makes apprehension difficult.

"They don't have horns; they don't look like monsters," McGaha said. "They're real congenial guys - that's why they're so good at it."

Most offenders know their victims and often coerce them with treats and rewards instead of threats, Powers said.

And most producers of child porn are motivated by sexual arousal, not profit.

When laws targeting child pornography first went into effect in the 1970s, commercial producers were more common. They sold images by mail but were mostly shut down in the 1980s.

Commercial sites surfaced again in the early days of the Internet, maintaining websites for paid subscribers. But again, they were put out of business fairly quickly.

Unfortunately, demand remained high.

The Internet, experts agree, brought child pornography out of the back alley and into the private home.

For people who would never "buy an adult porn magazine, much less something about children, it's a mouse click away now," said Plano police Detective Jeff Rich.

Complex investigations

Authorities knew from chat logs that Whitington talked about abusing a young boy. So when neighbors mentioned they'd seen a child coming and going from the apartment, the sense of urgency grew.

Hudson and McGaha, casually dressed with guns concealed, approached the building while the search team of a half-dozen armored agents remained behind. Whitington didn't resist and could have left while agents searched his apartment. Instead, he sat down to talk.

Within five minutes, he had confessed, McGaha said. Whitington gave agents his encryption key, enabling them to find the illegal material quickly.

Even with cooperation, child pornography cases take massive amounts of time and money to investigate, said Rich, the Plano detective.

Each computer image must be examined, and the images, which often number in the hundreds of thousands, can take weeks to sift through.

"It's not like it used to be where everybody's got a 30-gig hard drive," McGaha said. "Now we have terabytes."

Whitington's collection wasn't huge, but authorities say he didn't need images to experience sexual satisfaction:

He told them he'd been sexually touching the boy whom agents escorted away for several years.

Whitington pleaded guilty to the federal child pornography charges for ordering molestations online, but not guilty to a state charge of continuous sexual abuse of a child.

Whitington, who was sentenced to 16 years in federal court and 50 years in state prison, plans to appeal the state sentence.

Who they are

Profile of a typical child porn producer:

• Gender: 97 percent male.

• Race: 86 percent white.

• Average age: 41.

• Education: 47 percent have some college; 88 percent are high school graduates.

• Employment: 76 percent employed when arrested.

• Criminal history: 77 percent have no or only minor infractions.

• Relationship to victim: 68 percent personally acquainted with victim.

Source: U.S. Sentencing Commission