Supporters of the ShotSpotter gunfire-detection technology made emotional pleas Monday and tried a variety of ploys to save its use for Cambridge police, but city councillors voted for the city manager to turn off the system and remove its microphones within 90 days.
With a community debrief set for 6 p.m. Tuesday about the gun battle on Memorial Drive that took place May 11, acting police commissioner Pauline Wells and city manager Yi-An Huang urged councillors to wait on the vote until afterward.
“Look, it is our obligation to do everything we can do to keep our community safe,” Wells said. “We are literally going into a community meeting tomorrow night and telling them that the city of Cambridge voted down gunshot-detection technology after an active-shooter event.”
A majority of councillors, though, said that they saw no evidence that the system keeps anyone safe, including in the Memorial Drive incident – when a massive police response was on the way before a shot was fired by homing in on a suspect’s phone.
The vote went 5-2-2, with the majority led by policy order author Ayah Al-Zubi and her co-sponsors – Jivan Sobrinho-Wheeler, Marc McGovern and Patty Nolan – and winning the decisive support of mayor Sumbul Siddiqui. Those opposed to the end of the service were Tim Flaherty and E. Denise Simmons. Those voting “present” were Cathie Zusy and vice mayor Burhan Azeem.
Wells told councillors just hours after the gun battle that ShotSpotter did not hear the gunfire because that part of the city is “outside of the coverage area.” Spencer Piston, an associate professor of political science at Boston University who has given testimony to a council subcommittee on the tech, told councillors on Monday that it was his understanding a ShotSpotter microphone is installed about four blocks from where the shooter fired as many as 60 rounds from an assault rifle.
The sounds of gunfire were considered so intense by Middlesex district attorney Marian Ryan that she began a press conference that day by playing audio from the scene, more than 40 seconds of nearly relentless high-power weaponry going off. Yet “there was no alert” from ShotSpotter, Piston said.
When Al-Zubi went door to door with state representative Mike Connolly at the apartment building closest to where the shooting took place, she said Monday, she found residents who were “confused as to why we have this tool, when it did nothing to improve the response here.”
“I don’t know why we would want to tell them that we voted to keep a technology that had no benefit,” Sobrinho-Wheeler said. “I don’t want to tell our community that and pretend that we’re doing something that works when it doesn’t.”
Citing a “false narrative”
The technology, first installed in 2014, is unreliable and unproven, has a false positive rate of 82 percent of the time it triggers in Cambridge, doesn’t clearly meet the standards of the city’s Surveillance Technology Ordinance and never went through a public process for deployment like bike lanes, a housing development or a park redesign, Sobrinho-Wheeler said.
“If the city wants to go back and talk to residents, do the engagement around this technology and come back with different results, do that,” Sobrinho-Wheeler said.
The councillors fighting to keep ShotSpotter or at least delay the vote shared the argument that it’s a “false narrative” to think federal agents are monitoring conversations overheard by the always-on microphones of ShotSpotter, and Zusy agreed. That claim does not appear in the policy order that was voted Monday, and wasn’t raised by the order’s supporters on the council – though it is the kind of thing the council had in mind when adopting the Surveillance Technology Ordinance in 2018. “What this comes down to,” McGovern said, is “access to the information … Under this current federal administration, that scares me.”
Proponents of keeping the tech or delaying a vote tried further arguments.
“What worries me is this: The underlying problem of gun violence in our community is far from resolved,” Wells said, noting that in just the past two weeks, officers have taken three loaded guns off the streets in unrelated incidents, “some equipped with large-capacity magazines. In every case, the individuals carrying them were convicted felons who never should have had a gun in their hands. They were armed, and they were walking the same streets that we walk every day. Last Monday’s incident was an anomaly, and frankly, we’ve been lucky, but lucky is not a strategy.”
ShotSpotter without 911 calls
Wells also said there were at least 11 times that ShotSpotter detected gunfire in Cambridge and “not a single 911 call came in, not one.”
“That means 11 moments when no one reached for the phone, 11 moments when officers would have no direction, 11 moments when seconds were slipping away and ShotSpotter was the only reason help was there at all,” Wells said.
When Huang spoke after Wells, he mentioned that in these cases over the past 10 years, the ShotSpotter alerts “allowed us to go to the scene, pick up a casing, respond in case there was anything active going on and start an investigation” – meaning they were part of Cambridge’s preponderance of gunfire incidents in which weapons are fired but there are no victims. That left it unclear what “help” Wells was referring to in these cases.
A specific example of the value of SpotSpotter was cited by Wells from a July 2024 incident in which gunfire on Harvard Street critically injured a 48-year-old “local father” whose injuries required immediate medical care.
“Thankfully, due to the ShotSpotter activation and a prompt, precise response from nearby officers, that is what he received,” Wells said, afterward giving a dramatic reading to an excerpt from a police report.
At the time of that incident, an officer asked by radio whether ShotSpotter had activated. The response heard that night on the police scanner was no – ShotSpotter was not triggered.
Why perpetrators walk free
Simmons mustered several arguments in favor of ShotSpotter, including a repeat from the previous week about race. Decisions shouldn’t be made without “the voices of authentic people,” she said, referring to Black and brown people whom she feels have not been adequately polled. Despite the backlash it brought from Black and brown people speaking during public comment against ShotSpotter, Simmons at one point said she would defer to “anybody that lives in Newtowne Court and Washington Elms that’s here,” referring to public housing in The Port Neighborhood. Seeing none, she said, “As I thought.”
To Simmons, the technology seemed to be more than a way to alert police that a noise might be gunfire: “It may help the police or law enforcement in gathering sufficient evidence so that even in the absence of witnesses’ testimony, we can still hold people accountable,” she said.
Murders go unsolved in Cambridge because people who know the killers’ identity won’t come forward, Simmons said. But it is not because they are afraid of the criminals they might snitch on.
“Some people might say, ‘Well, they’re afraid of law enforcement.’ I would say there’s some people that are afraid of coming here, because if you have a difference of opinion, you’re shouted down, you’re disrespected,” Simmons said.
“These shootings were where there are often people who have information who are too afraid to come to City Council, let alone help the Public Safety Department. They distrust the city government, they distrust us. So we all have some work to do to make sure that people feel comfortable coming before us and talking,” Simmons said. “Because of this resistance to come before the council, perpetrators continue to walk free. I don’t think we ever found Charlene Holmes’ killer. We have never found Anthony Clay’s killer. I’m not here to bring up people’s names, because every time we do that for the person that’s still alive, it opens a wound, and I know that’s no one’s intention, to make people feel bad that already feel bad.”
Simmons tried to table the policy order eliminating ShotSpotter, but that attempt failed. The same five voting to end ShotSpotter voted against the tabling; the four who wanted delay included Simmons, Azeem, Flaherty and Zusy.
This post was updated May 19, 2026, to remove a reference to a parole system tracking device.
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