Cambridge Police Department implements ShotSpotter to locate gunshots

By P. Ryan Anthony, Special To Dorchester Banner
Posted 1/24/23

Cambridge has, unfortunately, become somewhat infamous for its rising crime rate, especially gun-related crimes. Part of the problem is that gunshots are not being reported to the police …

You must be a member to read this story.

Join our family of readers for as little as $5.99 per month and support local, unbiased journalism.

Already a member? Log in to continue.   Otherwise, follow the link below to join.

Please log in to continue

Log in

Cambridge Police Department implements ShotSpotter to locate gunshots


Cambridge has, unfortunately, become somewhat infamous for its rising crime rate, especially gun-related crimes. Part of the problem is that gunshots are not being reported to the police department.

“In certain areas where crime and shooting have happened,” said CPD Chief Justin Todd, “people have become accustomed to that and just will not call the police.”

Indeed, according to a report from the Brookings Institute, 88% of gunshot incidents go unreported. But Chief Todd is hopeful that Cambridge’s newly implemented detection technology, called ShotSpotter, will help remedy that.

The California-based company ShotSpotter, which has been in business since 1997, uses an assemblage of acoustic sensors to detect and locate gunshots by triangulating the sounds. They record the time and audio of loud noises that may be gunfire. After the incident is located, machine algorithms filter the data to classify the sound as a possible gunshot. The recording is sent to a technician in ShotSpotter’s Incident Review Center to determine if the noise is in fact from a gun. Should the technician decide the sound is a gunshot, its location is sent as a digital alert to the 911 Call Center or police officers in the coverage area. The whole process takes about 60 seconds.

“And when they send that signal,” said Todd, “it’ll tell us how many rounds were fired, and it also gives us the radius of so many feet away of where that gunfire came from.” (ShotSpotter claims it can get the police within 82 feet of the gunshot location.)

Taking into account the potential safety issues, officers can use a street view of the area on their device or computer and decide the most tactical way to approach and handle the situation. Had the incident happened before installation of the ShotSpotter equipment and someone called in sounds of gunshots, responding officers would have been forced to ride around the neighborhood looking for the correct location.

“Well, lo and behold, (on Jan. 12) when we got the gunfire, they went right to that area and were able to locate bullet holes in a house,” said Todd. “And they knew right then that was their crime scene. So, you’re shaving minutes, hours off an investigation.”

Importantly, this information can be used for acquiring search warrants. ShotSpotter recently sent officers to a particular area, where they found a shell casing. After the officers filed their report, detectives pulled up footage from city surveillance cameras and saw someone walk out of a house, fire off one round and go back in. From that, the police were able to obtain a warrant and search the house, where they recovered a large quantity of crack cocaine and ecstasy. All of this is admissible in court.

ShotSpotter has already led CPD to other warrants and arrests. For example, on Jan. 2, officers responded to an alert in the 700 block of Robbins Street and found evidence of gunfire. When they encountered a 31-year-old local man in the area, he turned out to have an arrest warrant in Talbot County.

“So, it’s getting us results now,” said Todd. “It hasn’t produced the guns we want yet, but I believe that will definitely come.”

CPD was able to use government grants to acquire the ShotSpotter tech. Valerie Mann has been their grant writer for many years and is very good at locating needed funding. Once that was in place, the ShotSpotter company came out and gave management training, followed by sessions for the officers. The equipment started going up around the city the last week of December, and the system was in use on New Year’s Eve. But CPD isn’t relying on just the new technology.

“We’re trying to get as much grant funding as we can to put up as many city cameras as we can, because they have proven time and time again to solve crimes,” said Todd. “Every homicide we had last year, some way, somehow, those cameras benefited us in the investigation.”

They are currently working on installing cameras on all the city’s playgrounds.

Cambridge also got a state grant for license-plate readers, which can pick up a vehicle fleeing a crime scene based on a vague description and direction. Four mobile units and two stationary units will arrive by the end of January and will be deployed next month.

As for ShotSpotter, Chief Todd has received only positive feedback from the community.

“I haven’t talked to a lot of citizens about it,” he said, “but the people I have spoken with, everybody seems very happy about it. And the word is, ‘Get it out, let people know that they’re going to show up at your door if you’re shooting.’ And that’s what I think I want to get out. We’ve got city cameras, we’ve got ShotSpotter, we are making changes that are going to make it harder and harder for a criminal to commit that crime.”

But the word on ShotSpotter isn’t all positive everywhere. In 2021, the company had a net revenue loss of $4.4 million, in part due to contract non-renewals and an increase in the costs from litigation. Some cities have decided that ShotSpotter creates too many false positives (reporting nonexistent gunshots) and false negatives (not reporting actual gunshots). It has been alleged that ShotSpotter sensors are deployed primarily in communities of color, leading to the detection of more incidents in those areas than in others. And there are claims that the company advises police departments on how to respond to requests from the public and media for their records.

Todd was quick to respond to these criticisms. “Our sensors are placed in an area that has been determined to have a high amount of gun crime, homicides and assaults with firearms. That is the determining factor of where the radius is placed in the city.”

He also stated that officers are encouraged to be out and visible in all communities of Cambridge.

But he did admit that the ShotSpotter software is overseen by real people who are vulnerable to human error. “If we determine that a reported gunshot was actually fireworks, we report that back to ShotSpotter as requested by them.”

Additionally, Chief Todd categorically denied that the company has ever told him how to answer requests from the public or media. “It’s early for us to gather data, but I have been happy with it thus far. With the ShotSpotter technology, along with other tools such as surveillance cameras, there is potential for success.”

Perhaps most important is a bright spot that has nothing to do with technology. Two new Cambridge police officers recently graduated from the academy and are now on field training. Plus, there are four or five applications in the job portal for the July class.

“That’s a good sign,” said Todd.

Members and subscribers make this story possible.
You can help support non-partisan, community journalism.