It was just before 3 a.m. on July 16 when Sacramento Police Department officers working in the north Sacramento area were alerted to possible gunshots fired in the Strawberry Manor neighborhood.
The department’s detection system, ShotSpotter, picked up the sound at the 100 block of Barton Way. Police were sent a pinpoint location of where the suspected gunfire took place, as well as an audio recording of the incident.
When officers arrived, they found a group of five people standing next to a car, a high-capacity handgun magazine on the ground and a handgun near the front of a nearby house.
A 16-year-old was ultimately arrested on several counts, including suspicion of discharging a firearm in a negligent manner, being a minor with a firearm and possessing a large capacity magazine, said Sgt. Bryce Heinlein, a Sacramento Police Department officer.
“It’s a great tool for us,” Heinlein said of the ShotSpotter technology. “It heightens our awareness when we know we are going to be confronted with suspects who may have firearms.”
Sacramento police and city leaders now want to expand their use of the technology, particularly to Oak Park after an uptick of violence in that neighborhood this summer. They say ShotSpotter has helped curb violent crimes elsewhere in the city.
On Thursday, the Sacramento City Council approved the department’s proposal to spend an additional $251,795 to continue using the tool.
“It’s the perfect merging of technology and our law enforcement officers being able to solve gun-related crimes,” said Mayor Darrell Steinberg. “We need to constantly be on the cutting edge of new technology. (ShotSpotter) is worth the money.”
Police currently rely on ShotSpotter sensors across two separate 3-square-mile areas, one in south Sacramento and another in the north area near Del Paso Heights. The sensors have had 1,096 activations from June 15, 2015 to May 31, 2017.
In that time frame, information captured by the sensors has led to the arrests of more than 89 people and the seizures of 90 guns, police say.
The department is also starting conversations with the Sacramento County Sheriff’s Department, which is responsible for parts of Oak Park surrounded by the city limits and could benefit from ShotSpotter technology, said Officer Linda Matthews, a Sacramento Police Department spokeswoman.
The Sheriff’s Department does not currently use ShotSpotter, said spokesman Sgt. Tony Turnbull.
Police will pay to extend the contract with ShotSpotter using money from Measure U, a half-cent sales tax approved in 2012 to fund public services, as well as money collected from seizing assets used in crimes.
The department debuted the technology in the North Sacramento area in 2015 at a cost of $150,000. In 2016, City Council approved the department’s request to spend an additional $365,000 to continue and expand the program into south Sacramento.
ShotSpotter technology relies on a network of sensors to detect when a gun is fired.
Though ShotSpotter would not say exactly how many of their sensors exist in either south Sacramento or North Sacramento, the company’s CEO and president, Ralph Clark, said it typically installs about 15 to 20 sensors per square mile. The number depends on the noise level, building density and type of terrain that exists in the area using the tool, among other factors.
“You can think of these sensors as being ears,” Clark said. “But these ears are designed to ignore anything other than a pop, boom or a bang.”
Once a loud noise is detected, the sensors analyze the sound waves to determine its location and whether the sound is consistent to that of gunfire versus that of other loud noises, like firecrackers or car backfires.
The information is sent to a ShotSpotter analyst for a final approval before being passed along to officers on the street. Police are alerted of the gunfire within 30 and 60 seconds of being detected by sensors, the company says. They are sent a pinpoint location on a map of where the firearm was discharged, accurate within 25 feet of the incident, an audio clip of the gunfire, as well as the number of rounds shot, Clark said.
Overall, the sensors help alert law enforcement of any outdoor gunfire detected in the area they cover, regardless of whether anyone calls police. Heinlein and Clark both said gunfire is generally under-reported, especially in communities where gun violence may be more common, or normalized.
The technology also increases engagement with community members, with officers instructed to knock on doors and talk to neighbors when a clear suspect is no longer at the scene, Heinlein said.
Of the activations recorded by ShotSpotter sensors in Sacramento, about 25 percent were accompanied by citizen reports of gunfire.
“Before, we relied on the community to make calls for service or to report gunfire in their neighborhood and if we were lucky, we’d be driving in the area where the gunfire occurred,” Heinlein said. “(ShotSpotter) is a way for us to be more accurate in these incidents.”
ShotSpotter technology is not perfect, however. The outdoor sensors installed in Sacramento are not effective in detecting gunshots inside a home, Clark said. The company offers law enforcement agencies an 80 percent guarantee of their accuracy, though Clark says actual results are much higher.
Brian Hofer has examined ShotSpotter for years and is currently the chairman of the Privacy Advisory Commission in Oakland, whose police department uses the technology.
He is skeptical of the number of arrests and gun seizures Sacramento Police Department says it has made using ShotSpotter. Hofer said the Sacramento figures far outpace results seen in other cities around the country that have adopted the technology.
“No one’s having that type of success,” he said. “It’s awesome if it’s true, and that would explain why Sacramento wants to expand its (ShotSpotter) system.”
The sensors also raise a concern over mass surveillance and potential misuse of ShotSpotter’s audio recording capabilities, he said.
“Anytime that you have microphones located in your city, there’s going to be a privacy impact,” Hofer said. “I do have an expectation to not be recorded and certainly not by a company that is selling alerts to public law (enforcement).”
Hofer pointed to a 2007 case in which ShotSpotter microphones picked up the voice of Tyrone Lyles after he was shot in the stomach. His last words, in which he called out the nickname of his accused shooter, were used by prosecutors in the homicide case to win a second-degree conviction.
Clark said the case was a rarity, with the words captured only because Lyles was screaming out immediately after the shooting occurred.
“Our field of vision is extremely narrow,” he said, adding that the sensors only record a few seconds before and after shots are detected. “We are only interested in reporting and detecting outdoor gunfire.”
Some community groups say they support police use of ShotSpotter.
“I support the law and order,” said Scott Song, a spokesman for the Asian American Public Safety Service Center, a community group that formed after a string of robberies targeted Asian American residents in south Sacramento last year. “I believe, baseline, the police are protecting our community.”
His parents live in south Sacramento, where he says gunfire is not uncommon.
Derrell Roberts, CEO for the Roberts Family Development Center, a youth program located off of Del Paso Boulevard, also backed ShotSpotter, saying it has made a noticeable difference in his community.
City Council District 2, which includes Del Paso Heights and Old North Sacramento, saw a 10 percent decrease in violent crime last year, more than any other district. Police credited ShotSpotter as part of the solution.
“We have far too many incidents where violence has been an unnecessary part of our community,” he said. “So, anything that would help us reduce or eradicate gun violence, I would have to support.”