A ShotSpotter sensor seen atop a Park District fieldhouse in 2024. Credit: Jim Daley

This story was co-published in collaboration with WIRED.

When mayor Brandon Johnson announced in February that Chicago would stop using the gunshot-detection system known as ShotSpotter by year’s end, local activists were elated.

Ever since 2021, when the police fatally shot thirteen-year-old Adam Toledo while responding to a ShotSpotter alert, the Stop ShotSpotter Campaign has been pressuring the city to ditch the technology. Johnson’s decision not to renew the Windy City’s contract with ShotSpotter was seen as the culmination of the campaign’s efforts.

But ending the contract may not be enough to remove the company’s more than 2,500 sensors from neighborhoods on the city’s South and West Sides, where they’re disproportionately located. Internal emails reviewed by South Side Weekly and WIRED suggest ShotSpotter keeps its sensors online and, in some instances, provides gunshot detection alerts to police departments in cities where its contracts have expired or been canceled. The emails raise new questions about whether the sensors in Chicago will be turned off and removed, regardless of Johnson’s decision.

“We continue to focus on serving the City of Chicago with our critical gunshot detection technology service during our contractual term,” a ShotSpotter spokesperson wrote in a statement. “Nothing has changed regarding our singular purpose to close the public safety gap by enabling law enforcement agencies globally to more efficiently and effectively respond to incidents of criminal gunfire…where gunshot wound victim’s lives are in the balance.”

An organizer who’s been active in the push to cancel ShotSpotter’s contract in Chicago wasn’t surprised the company has continued to work with police behind the scenes in cities where contracts have ended.

“I think it’s exactly what cops and corporations do,” says Nathan Palmer, an organizer with the Stop ShotSpotter Campaign and Black Youth Project 100. “Especially when we’re thinking about Chicago, it would benefit ShotSpotter to keep the mics up and working so that they can also throw lobbying money at whoever’s gonna oppose mayor Brandon Johnson in the next election.” 

ShotSpotter, which rebranded as SoundThinking in 2023, has a customer base of roughly 170 cities, according to its most recent filing with the US Securities and Exchanges Commission. Chicago is not the first to deem the ShotSpotter technology not worth the cost. (By the time the city’s contract extension ends in November, ShotSpotter will have cost Chicago more than $57 million since then-mayor Rahm Emanuel inked a comprehensive deal with the company in 2018.) 

San Antonio, San Diego, and Dayton have all joined a growing list of cities that have publicly cut ties with ShotSpotter. Confidential company emails reviewed by the Weekly and WIRED, however, indicate that the company never completely pulled its technology out of some cities.

An October 2023 email sent to John Fountain, a director of field and network operations at SoundThinking who left the company in December, described how the company continued to secretly offer its help to police in cities where contracts had lapsed. The email, which addressed a shortage of sensors in a city with an active contract, apparently referred to Clark Dunson, SoundThinking’s director of systems engineering.

“I would like to imagine we can pull some [sensors] from an old coverage area … Maybe San Diego and Indianapolis,” wrote the sender, whose name was redacted. “Last time we looked to remove sensors from an old coverage area I know Clark flipped out since we still work with police using those sensors (which I did not know).”

A spokesperson for the company declined to answer detailed questions about what services the company has provided to police departments after contracts are up and emailed a statement instead. “SoundThinking believes this confidential information was illegally disclosed by ex-employees and is currently pursuing civil and criminal remedies against the private parties responsible,” the statement read. “Due to this ongoing litigation, we cannot comment specifically on the leaked materials; however, we will continue to object to the use of our stolen data and reinforce the safety and privacy risks of disclosing individual sensor locations.”

ShotSpotter is suing two former employees who the company alleges posted confidential company information on Twitter after one was fired last November. 

In February, WIRED reported ShotSpotter sensor locations based on leaked company data showing more than 25,000 microphones arrayed across the globe. Those maps revealed active sensors remained in both San Diego and Indianapolis. The Indianapolis Metropolitan Police (IMP) recently told the IndyStar that they do not have a contract with the company after piloting technology from three different gunshot detection companies in 2022.

“The evaluation of whether or not gunshot detection technology system is right for Indianapolis is still ongoing,” a police spokesperson told the IndyStar. The statement added that the department believed it was ShotSpotter’s responsibility to remove its sensors.

ShotSpotter doesn’t sell its sensors to cities. Instead, the company uses a “software-as-service” model, billing cities for the software and applications that allow police to access ShotSpotter alerts. When a contract expires, the company apparently doesn’t always retrieve its sensors.

An email from Fountain dated from December 2022 estimated that there were a “few hundred sensors still installed” in San Diego and that they are “active even if the market isn’t.”

Fountain noted that removing any sensors from San Diego would require Clark Dunson’s approval. “Clark is really pushy and he likes to tinker around with those coverage area[s] but I imagine we can pull a few here and there,” he wrote. 

In August 2023, Dunson sent an internal email that said ShotSpotter had been providing “test alerts” to police in San Diego and San Antonio. “As a last resort we can pull sensors away from San Diego or San Antonio if needed but Lee [Lim, a SoundThinking tech-support engineer] has been working with the PD in those areas giving test alerts and tracking down detections for them.” 

The San Diego Police Department (SDPD) denied that sensors in that city are active or collecting any data. SDPD also claimed to never have asked the company for help with gunshot detections in any incidents involving homicides or shootings.

“At this time, there is no contract and there is no plan to move forward with the company,” a spokesperson for the department wrote in an email. San Diego and ShotSpotter entered into an agreement that allows the company to leave its sensors on city property. “However, as of September 2021, the equipment is deactivated, cannot collect any data, and is inoperable.” 

But emails the Weekly and WIRED obtained via a California Public Records Act request show that ShotSpotter stayed in touch with SDPD for more than 15 months after the city’s contract expired in September 2021. In those emails, ShotSpotter support staff routinely address SDPD as a “ShotSpotter Customer.”

These weren’t just mass marketing emails that all customers past and present are frequently subjected to. The emails we obtained show that in October 2021, after the contract had lapsed, ShotSpotter also provided an SDPD officer with an “investigative lead summary” about a shooting in San Diego, including the precise location and the number of rounds detected, upon SDPD’s request.

ShotSpotter also sent SDPD emails updating the department about routine scheduled maintenance in October 2022 and how the company planned to address the “extremely high volume of fireworks activities” around New Year’s Day in 2023.

“Despite our efforts, we may occasionally miss a gunshot in error,” wrote Dinh Nguyen, a technical support engineer at ShotSpotter, in a December 2022 email to SDPD. “You may also experience some delays in the publication of incidents.”


ShotSpotter is not on a list of surveillance technologies the SDPD are required to frequently publish as a part of a sweeping surveillance ordinance passed by the San Diego City Council in August 2022 and amended in January of this year.

A San Diego city council member whose district includes several of the neighborhoods where ShotSpotter sensors were installed in 2016, said that their “office is aware of the ShotSpotter situation” via a spokesperson. In July 2021, the then-District Four councilmember requested the city remove sensors from his district, which helped scuttle the contract renewal.

“A request to remove such [sensors] has been forwarded to the San Diego Police Department and the Mayor’s office,” a spokesperson for current District Four councilmember Henry L. Foster III (who was sworn in in April) wrote in an email to the Weekly and WIRED. “Devices that have not been approved in accordance with the Surveillance Ordinance should not be installed and or operational by the City of San Diego or third party.”

San Diego mayor Todd Gloria’s office did not respond to requests for comment.

In 2021, San Diego’s city council pulled a scheduled vote on a four-year extension to ShotSpotter from its agenda, effectively sunsetting the city’s agreement with the company. Although Gloria’s office said in statements at the time that they would bring the extension back up in the city council, there is no indication that they did.

Based on a map of the secret locations of every ShotSpotter sensor in the country published by WIRED, there are still about 30 active sensors in San Diego, most of which are clustered near the University of California, San Diego’s La Jolla campus and the Scripps Institution of Oceanography.

When asked to comment on whether SDPD receives and responds to ShotSpotter alerts from these active sensors, a spokesperson for the department directed questions to the UC San Diego police. UCSD did not respond to requests for comment.

The Weekly and WIRED requested emails sent between San Antonio Police Department (SAPD) and ShotSpotter dated after the city’s contract with ShotSpotter expired in the fall of 2017. In March, the SAPD filed an appeal with the Texas Attorney General, seeking to have the responsive records withheld under a laundry list of exemptions provided for by the state’s public records act. The police provided sealed records to the Texas AG to review. The AG is expected to decide whether to release the records by May.

SAPD said that after the contract lapsed, they never asked ShotSpotter for assistance and no arrests were made based on detections provided by the company.

Records produced in response to a separate public records request show that ShotSpotter sent four-term San Antonio mayor Ron Nirenberg at least two marketing emails months after the city council voted not to include ShotSpotter in its budget for the upcoming fiscal year. The company does not appear to have communicated with his office after November 2018, however. Nirenberg’s office did not respond to requests for comment.

“To me it sounds like, on their part, another strategic business decision, and that’s what they’re doing in every city,” says Palmer, the Stop ShotSpotter organizer. “It sounds like a business decision, because they don’t actually care about public safety.”

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Jim Daley is the Weekly’s investigations editor. Max Blaisdell is a fellow with the Invisible Institute and a staff writer for the Hyde Park Herald.

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