Analysts working for ShotSpotter, a gunshot detection system, are accused of manually altering police evidence at the request of police officers, according to court documents reviewed by Motherboard. Testimony from cases across Chicago, Illinois and New York State suggests that some officers are “grasping for evidence that supports their narrative of events,” Motherboard reports. More than 100 cities across the country are reportedly using the technology. 

One Chicago case involves 25-year-old Safarain Herring, who was shot in the head and dropped off at a local hospital on May 31, 2020 by a man named Michael Williams. Herring died two days later. Motherboard reports:

Chicago police eventually arrested the 64-year-old Williams and charged him with murder (Williams maintains that Herring was hit in a drive-by shooting). A key piece of evidence in the case is video surveillance footage showing Williams’ car stopped on the 6300 block of South Stony Island Avenue at 11:46 p.m.—the time and location where police say they know Herring was shot. 

How did they know that’s where the shooting happened? Police said ShotSpotter, a surveillance system that uses hidden microphone sensors to detect the sound and location of gunshots, generated an alert for that time and place. 

Court documents, however, assert that this evidence was falsified. Motherboard continues:

That night, 19 ShotSpotter sensors detected a percussive sound at 11:46 p.m. and determined the location to be 5700 South Lake Shore Drive—a mile away from the site where prosecutors say Williams committed the murder, according to a motion filed by Williams’ public defender. The company’s algorithms initially classified the sound as a firework.

But after the 11:46 p.m. alert came in, a ShotSpotter analyst manually overrode the algorithms and “reclassified” the sound as a gunshot. Then, months later and after “post-processing,” another ShotSpotter analyst changed the alert’s coordinates to a location on South Stony Island Drive near where Williams’ car was seen on camera. 

“Through this human-involved method, the ShotSpotter output in this case was dramatically transformed from data that did not support criminal charges of any kind to data that now forms the centerpiece of the prosecution’s murder case against Mr. Williams,” the public defender said in the motion reviewed by Motherboard. 

This pattern of analysts altering evidence at the request of officers appears to be a frequent occurrence based on the Herring case, as well as other trials in Chicago and New York State. The ramifications of that could be huge for ShotSpotter in Chicago, “where the technology generates an average of 21,000 alerts each year,” according to Motherboard. 

Some of the biggest questions about ShotSpotter are around the technology and whether or not it actually works, “in terms of its sensor accuracy and the system’s overall effect on gun crime,” according to Motherboard. The company so far hasn’t allowed any independent testing of its algorithms, and any claims of accuracy by ShotSpotter were generated by marketers and not scientists, the company admitted in court. 

Chicago, according to Motherboard, is one of the most important cities for ShotSpotter, and is quickly becoming “a battleground over its use.” The city’s $33 million contract with the company is coming to an end this summer, and city officials must decide whether or not to renew it.

Civil rights activists are calling on Chicago to abandon the technology, which they say endangers the lives of Black and Brown people. “These tools are sending more police into Black and Latinx neighborhoods,” Alyx Goodwin, a Chicago organizer with the Action Center on Race and the Economy, one of the groups leading the campaign, told Motherboard. “Every ShotSpotter alert is putting Black and Latinx people at risk of interactions with police. That’s what happened to Adam Toledo.”’