(CNN) -- When John Shehan joined the National Center for Missing and Exploited Children in 1999, people looking to create and share child sexual abuse material online belonged in the dark corners of the internet, he said. They had to purchase digital cameras and video recorders, wait on slow dial-up connections to upload content and find designated chat rooms with like-minded individuals.
Today, children can be easily photographed and recorded on mobile phones, high-speed internet has become available around the world, and social networking sites have gained popularity. All of this has made it easier to create and share child sexual abuse material, explained Shehan, who is now the vice president of the center's Exploited Children Division.
"It's a much more interconnected world now," he said.
But the same interconnection that puts children at risk is now being used to find them when they go missing, and rescue them when they're being exploited.
The old way: Posters and faxes distributed locally
Years ago, when a child was reported missing, the search involved creating posters and fliers that were distributed in the neighborhood and then faxed them to other jurisdictions if officers believed that the child may have been taken elsewhere, Shehan explained.
"Back in 1984, John Walsh, our founder, used to talk about how it was easier to track and find a missing car or a horse than it was a missing child," he said.
The system was cumbersome and not well-connected, he added.
Beyond paper fliers, law enforcement around the world did not have established systems to share the information online.
"Twenty years ago, we realized many law enforcement agencies did not know how to create websites or photos of missing kids online," said Caroline Humer, director of the International Center for Missing and Exploited Children. The organization has since created a system, known as the Global Missing Children Network Engine or GMCNgine, that allows law enforcement in 29 member countries to quickly create electronic posters in their local language.
The posters are just one part of what the GMCNgine has become.
The new way: Geotargeting, facial recognition and engines that never give up
"We wanted to build an engine that allows law enforcement to explain to these families that there is a system out there that will never stop looking for your child," Humer said. The engine "never ends, never sleeps, never gives up; it never has a change of shift. It is a system that essentially runs 24/7, 365 days until the child is found ... regardless of how long the child has been missing."
Once the GMCNngine creates a poster with a missing child's information, it submits it to both local law enforcement and the Federation for Internet Alerts, which then sends an alert to everyone in the geographic region where the child is believed to be missing. It works by taking over advertisement space on individual websites, explained Jason Bier, president of the Federation for Internet Alerts.
As people browse the web, rather than seeing an ad for clothes or shoes, they see an alert about a missing child.
"We have links in the alerts that, if you click them, you can look at a missing child poster," he said. "We see millions of people that have looked at posters as a result."
In addition to the alerts, the GMCNgine uses facial recognition software to search for pictures matching that of the missing child.
The global nature of the engine is particularly important, Humer explained, adding that a child can go missing at any time, anywhere, regardless of background, income or demographic. Similarly, the internet knows no boundaries, she added.
Facial recognition software has recently come under scrutiny for some of its biases in identifying women and people of color. The American Civil Liberties Union has alsoraised privacy and effectiveness concerns. But Humer says artificial intelligence, and specifically facial recognition software, is used to narrow the field and keep investigators from having to comb through thousands of photos. Investigators then look at all the images the software presents as leads.
Similar software is used to find exploited children who may or may not be missing.
Finding trafficked children
In recent years, technology companies have stepped up to help law enforcement find children who are trafficked online.
One of these is Thorn, a startup that partnered with the technology company Digital Reasoning to create a sex trafficking investigation tool known as Spotlight.
According to a survey conducted by the company in 2012, 75% of child sex-trafficking survivors had been sold online, most through escort websites.
Spotlight finds images of minors in those ads, again helping law enforcement work through cases faster.
"We build software to help those in the front lines do their job better," said Julie Cordua, CEO of Thorn.
Since its launch four years ago, Spotlight has helped officers in the United States and Canada open more than 21,000 trafficking cases and identify about 18,000 victims, including more than 6,000 children, according to the company's data.
Spotlight and the GMCNgine work separately: One looks for exploited people, including children, and the other looks for missing children.
"What we do hope in the future is that we can connect these two together to make sure that if a child is missing and is being trafficked, our systems will pick that up," Humer said. "That is the challenge for law enforcement. They only have one piece of the puzzle, so we are trying to give them as many pieces to put it all together."
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