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Tracking Criminals with GPS

Posted on February 16, 2016
What are satellites tracking? They're probably just helping you find the closest coffee shop, track your latest workout, or arrive safely on your next flight. But for people under house arrest, on probation, or out on parole, GPS is increasingly being used to monitor their whereabouts. Today’s WatchBlog navigates the web of criminal offender tracking systems. Where do you think you’re going? Some criminal offenders are tracked to determine whether they are breaking the terms of their probation or parole. In those cases, hardware, like an ankle bracelet, sends data about an offender’s location to law enforcement agencies. For high-risk offenders, GPS’s ability to track locations accurately and in near-real time supports other tools traditionally used to supervise them.

Figure 3: Global Positioning System (GPS)–Based Offender Tracking System(Excerpted from GAO-16-10)

Given the advantages—and dozens of states’ mandating its use—it’s no surprise that GPS is becoming a popular way to track offenders. But like a lot of newer technologies that don’t yet have clear industry standards, criminal justice agencies have to rely on their own field testing or vendors’ assertions about how and how well these systems perform. Heading in the right direction To ensure that offender tracking systems meet certain minimum performance requirements, the Department of Justice began working with criminal justice stakeholders and technology experts to develop offender tracking system standards. We took a look at DOJ’s draft standards—expected to be published by March 2016—and found that they addressed common needs and challenges, including
  • Location accuracy, both indoors and out. For example, systems should be accurate within 10 meters 90% of the time if there are no obstructions.
  • On-demand location within 3 minutes of a request.
  • Zones, or geofencing, designating certain areas an offender may be restricted to, like home or work, or prevented from, such as a victim’s home or a state border.

Figure 7: Example of Inclusion and Exclusion Zones (Excerpted from GAO-16-10)

  • Alerts for when an offender tampers with or removes the tracking device, violates zone rules, or begins losing the GPS signal due to poor coverage or a low battery.
  • Optional requirements such as detecting GPS signal jammers.
Beyond these standards, DOJ provides guidance but avoids offering a one-size-fits-all policy solution in recognition of the range of agencies, resources, and objectives of offender tracking. For more information on tracking criminal offenders, check out our full report.
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