DENVER (CBS4)– Technology designed to detect gunfire in high-crime neighborhoods is proving so successful, the Denver Police Department is expanding the program for another year.

DPD began using ShotSpotter in January in an effort to help officers respond to the exact location of a shooting. The high tech microphone sensors pick up where shots are fired and alert officers nearby. On average, Denver Police claim ShotSpotter alerts them 38 seconds after the first gunshot is fired and zeroes in on the shooter’s location within 82 feet.

“The officers are getting it the same moment as the dispatchers are getting it,” Denver Police Captain Steven Carter said. “They’re getting an audible and visual alert in their car and they get a little map that pops up that says this is where the shooter is standing. They’ll get and they can be responding long before the dispatcher sends them.”

Already this year officers have received 337 ShotSpotter alerts or about 40 per month, according to Denver Police. Of those incidents, 26 suspects were arrested immediately.

“Quite frankly it doesn’t sound like a lot,” Carter said, “but those are arrests of those we either caught at the scene or people who we were able to identify and quickly arrest near the scene. What that doesn’t count is all the evidence that we gather that lead to the arrest and the filing of charges on everybody else from what we were able to do with our investigation and later on charge them.”

(credit: CBS)

(credit: CBS)

Carter also said most of the ShotSpotter alerts did not have corresponding calls into 911 from citizens.

“In two-thirds of alerts we get from ShotSpotter no citizens called us,” Carter said. “So what that tells us is we would’ve missed 66 percent of the gunfire incidents in that area were it not for ShotSpotter.”

A concern many citizens have is if ShotSpotter can be used to eavesdrop on the public. Carter said while he understands that concern, the technology does not allow for live listening and that ShotSpotter’s privacy rules are strict on that issue.

“What the microphones are listening to are the sound and impulse made by gunfire,” Carter said. “Occasionally you can hear screaming.”

DPD will not reveal exactly where ShotSpotter sensors are located in the city or where they want to expand their coverage, but said the decision on where to place them is “data driven.”

“The entire city doesn’t need to be covered by ShotSpotter,” Carter said. “Most of the city is exceedingly safe, but we’re working with our crime data people to tell us where is the largest concentration of gun violence and those are the areas where we’re going to work on putting ShotSpotter.”

The Bureau of Alcohol, Tobacco and Firearms is funding the program for Denver this year, but the police department said it is looking into other funding options to keep expand ShotSpotter in 2016.

“It typically costs about $55,000 per square mile for one year,” Carter said. “It’s a lease system. We don’t buy equipment, we don’t buy software so there’s nothing for us to maintain. ShotSpotter does all the maintenance and upgrading.”

DPD would not say how much money they will spend on ShotSpotter, but according to the mayor’s proposed city budget for 2016, $195,000 would be dedicated to expanding the technology.

Kelly Werthmann joined the CBS4 team in 2012 as the morning reporter, covering national stories like the Aurora Theater Shooting and devastating Colorado wildfires. She now reports for CBS4 News at 10 and is always open to story ideas. Connect with her on Facebook or Twitter @KellyCBS4.