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CHICAGO — There’s a record number of people on Cook County’s electronic monitoring program. But it’s not just the size that’s changing. The Cook County Sheriff’s office is rolling out new GPS ankle bracelets to help better track the people in its program.

In the second of this two-part series, “WGN Investigates” offers a rare look at how the technology works, riding along with sheriff’s deputies as they search for people on the move.

Officers say a majority of people don’t wander too far.

But as we reported in Part 1 of our series, the number of people in Cook County’s EM program who are listed as AWOL now stands at 456, a 25% increase over last year.

Though, the sheriff’s office believes that number will decline as more people transition to GPS.

About half of the more than 3,200 people on EM now have the technology. It replaces the older radio frequency bands that were easier to remove and limited in terms of tracking.

Sheriff Tom Dart said before it wasn’t worth the cost to upgrade because most people on EM were accused of low-level, non-violent offenses.

“Now, there’s a different level of people being put on there,” Dart said.

Case in point: The number of people on EM accused of murder has jumped 212% to 53, since 2016. Those charged with criminal sexual assault has increased 232%; aggravated assault up 800% and more.

“The GPS is, boy, right time, right place,” Dart said. “And it’s really helpful given the violence in the city.”

Sheriff’s officers can track people in real-time. They receive alerts if someone leaves the house or tampers with the bracelet.  

“It made no sense that current electronic monitoring didn’t take advantage of GPS,” Steven Levitt, a University of Chicago professor and co-author of Freakonomics, said.

Levitt is helping the sheriff’s office analyze the GPS data.

He’s found that “when people are on this technology, they understand that when they commit crimes they are going to be caught. [So] consequently they commit fewer crimes.”

That’s what Dart is banking on.

“Communities will be safer because of it,” he said