September 24, 2018

Predicting a predator: Purdue AI tool identifies online deviants before they act

WEST LAFAYETTE, Ind. — Technology provides child predators with a means to troll for targets online, but a pair of Purdue University researchers have harnessed the power of artificial intelligence to help catch sex offenders before they make physical contact with the children.

With statistics suggesting that up to one in 25 children are sexually solicited online, the technology has the potential to make an impact.

Called the Chat Analysis Triage Tool (CATT), it uses natural language processing techniques to analyze conversations between minors and child predators and determine which adults are most likely to be “contact offenders,” that is, people who actually seek to meet children in person.

Kathryn Seigfried-Spellar, assistant professor of computer and information technology, and Julia Rayz, associate professor of computer and information technology, will give a joint talk about their “digital forensics tool” at Dawn or Doom ’18, Purdue’s annual conference on the risks and rewards of emerging technologies. Dawn or Doom will be held on Purdue’s West Lafayette campus Nov. 5-6. The conference, now in its fifth year, is free and open to the public. Visit the Dawn or Doom website for more information and a full list of speakers.

Dawn or Doom is aligned with Purdue's Giant Leaps Sesquicentennial Campaign and is part of the Ideas Festival theme, Giant Leaps in Artificial Intelligence, Algorithms, and Automation: Balancing Humanity and Technology. The Ideas Festival is the centerpiece of the campaign and connects world-renowned speakers and Purdue expertise in a conversation on the most critical problems and opportunities facing the world.

“From a law enforcement perspective, they have to deal with hundreds of these cases and they can be really overwhelmed,” Seigfried-Spellar says. “If they have a tool that quickly reads these chats and flags the ones that are at risk for being contact offenders, then law enforcement officers can better prioritize which cases need to be investigated first.”

In partnership with the Ventura County Sheriff’s Office in Ventura, California, Rayz and Seigfried-Spellar conducted hypothesis testing on real chats between minors and offenders. Because offenders in different parts of the country may speak in different ways or have different strategies for luring in children, they’re working on using data from around the country, including Indiana, to improve the tool.

They plan to make CATT freely available to law enforcement. One of their priorities when developing the tool was to make it easy to use for someone without any training in computer science.

They hope CATT will eventually be used not only to triage cases, but also to train police officers to become better decoys. Officers typically receive similar training and, thus, talk to offenders in a similar way. The Purdue researchers hope that the tool will help officers vary their language and be less detectable by offenders.

The researchers say there’s already a great deal of interest from the law enforcement community. After presenting at a conference for law enforcement intelligence analysts, Seigfried-Spellar and Rayz had people asking about developing a similar tool for everything from sex trafficking to drug crimes. It’s on their radar, but continued work on the initial tool will probably always be necessary.

“No matter how perfect the tool is, it will never be a done deal,” Rayz says. “When people suspect they’re being watched, their behavior changes, and the tool will have to adapt to those changes.”

Although this crime-fighting tool may represent a “dawn” – an example of technology being used for good – there also could be “doom” scenarios if it falls into the wrong hands. For example, a criminal who gets access to the technology might use it to escape detection.

Dawn or Doom ’18 features four tracks: Machines, Mind, Body and Data. Featured speakers at the conference include Frank Pasquale, law professor at the University of Maryland who specializes in artificial intelligence law; Naomi Grewal, global head of insights at Pinterest; and Nicholas Carr, author of New York Times best seller “The Shallows: What the Internet Is Doing to Our Brains.” 

Writer:  Adrienne Miller, 765-496-8204, 

Sources: Kathryn Seigfried-Spellar, 765-494-2439,

Julia Rayz, 765-494-9525,

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