Runner’s World typically covers fitness tips, inspiring athletes, and other content for exercise buffs, but the magazine recently featured a different type of story: The unusual tale of a “health-conscious assassin,” as they termed him, whose identity as a mob hitman was revealed by data from his GPS watch.

Brit Mark “Iceman” Fellows was convicted of two counts of murder after police came across a race photo of him with his GPS watch, which tipped them off to seize the device and analyze the data. Their analysis revealed Fellows’ reconnaissance activity, including his various travel speeds, enabling them to determine whether he was biking, walking, or at rest as he planned out the attack.

While obviously a unique situation, this raises some interesting questions.

As Cale Guthrie Weissman put it in Fast Company, “We know that Alexa is listening and phone carriers are selling your location data. But until now, we didn’t know your fitness tracker was cluing the authorities in about your [criminal] history.”

Of course, solving crime is not the only way law enforcement can benefit from wearables. The technology is now a major part of safety initiatives for police and the military, providing a critical link to communication and dispatch when they’re on a call or on patrol. According to Reg Jones, Samsung’s public sector solutions director, “Wearables represent the new era in police safety and situational awareness. They can augment other technologies used by officers as well as function as a standalone communication device.”

This is certainly true in the professional setting, but it’s important that military and other law enforcement personnel are conscious of what their personal use of wearables may reveal. For example, last year it came to light that information collected by a fitness app was inadvertently exposing the location of secret military bases and patrol routes. At the time, a Pentagon spokesman said, “We are reviewing the situation to determine if any additional training or guidance is required, and if any additional policy must be developed to ensure the continued safety of DoD personnel at home and abroad.”

In this particular case, the company behind the fitness app took some corrective steps to remedy the issue, but it likely won’t be the last example of IoT data leading to an unforeseen security vulnerability. Given the highly sensitive nature of law enforcement activities, this is an issue that everyone in the industry should be aware of.

While the criminal underworld may be currently less conscious of this possible mode of detection, we can expect to see more cases cracked when investigators gain more access to fitness trackers and other wearable data.