Boston Police Commissioner William Evans says he would support legislation on Beacon Hill to require search warrants to specify whether cell phone location trackers—known as StingRays—would be used in searches, he said on Boston Public Radio Wednesday.

"We have nothing to hide," he said.

The trackers, when activated, are able to show the location and phone number of all devices in a given area—not just the information from a single suspect being tracked, according to a recent investigation by the New England Center For Investigative Reporting. That's one of the reasons why civil liberties organizations like the ACLU have called for search warrant applications to include whether or not a tracker will be used, arguing that information allows judges to more effectively limit the scope of warrants granted.   

Cell phone trackers are used by other police departments across the country, including in Washington, Virginia, Minnesota, and Utah—states which all require search warrants to specify whether the technology is used. Other departments, like the New York City Police Department, have released records about how often trackers are employed and why, according to NECIR.

Evans said that, when using trackers, officers would zero in only on the number belonging to suspects.

"We're just focusing on a certain number that's someone who's a violent threat, that's the number we want," he said. "There's no personal data."

But Evans would not specify what kinds of situations would trigger the usage of the technology, nor whether there were oversight mechanisms in place to prevent its abuse, saying he would need to consult his legal team before he was able to release such information to the public.

"It's only where exigency exists and lives could be at stake," he said.

Evans expressed frustration at the pushback on the cell phone tracker usage.

"Every man thinks we're snooping and digging into their lives and the police are doing everything sneaky," he said. "This is about public safety. There's no sinister plot here."

"We get held to high standards when it comes to solving homicides, but we need the tools," Evans said.

William Evans is the commissioner of the Boston Police Department. To hear more from Commissioner William Evans, tune in to Boston Public Radio above.