Menu
« Back to News

EXCLUSIVE: NYPD ShotSpotter gunfire sensors improve rates of 911 calls, arrests

March 28, 2017
NY Daily News

They’re hearing something and finally saying something.

Two years ago, the first ShotSpotter gunfire sensors were installed in Brooklyn and the Bronx amid great concern that far too often — about 80% of the time — New Yorkers who heard shots didn’t bother calling 911.

Since then, the rate has improved — with 34% of shootings detected by ShotSpotter also resulting in a 911 call, according to 2016 statistics.

The rise comes as both arrests by police and complaints against officers are down substantially while the department adheres to a new policing philosophy that stresses a closer relationship between cops and the neighborhoods they serve.

Deputy Commissioner Jessica Tisch, the NYPD’s technology guru, said the sea change is affecting the way New Yorkers think about the NYPD.

“We know that based on neighborhood policing that the NYPD is making significant efforts to partner with the communities and we also know that cops are responding more to shots fired jobs because they know about more shots being fired,” Tisch said. “The numbers show more people are engaging with police.”

Sgt. Joseph Freer, who works with Tisch on the ShotSpotter initiative, said that even though the alerts are sent to cops’ smartphones and beat the average 911 caller by almost two minutes, the added value of an eyewitness or earwitness is immeasurable.


Arrests by police and complaints against officers are down while the NYPD adheres to a new philosophy that stresses a closer relationship between cops and the neighborhoods they serve. (Mathew Sumner/AP)

"We can't have cameras everywhere," Freer said. "We need human eyeballs, so getting that citizen call is just as valuable. We'll get there quicker with ShotSpotter but I'd still love to tie it to witness descriptions."So, we want the people engaged and this increase is very heartening to see."

Cops said knowing about more shootings gives them the ability to find more guns and more bullets, make more arrests and tie more incidents together.

In 2016, for instance, police responding to 2,399 ShotSpotter alerts recovered guns in 57 incidents — weapons that were either left at or near the scene or recovered during the execution of search warrants.

Most of those incidents — 37 in all — were accompanied by 911 calls. However, 18 were not — meaning that without ShotSpotter those guns would still be on the street, Freer noted.

Many other times, Freer said, ballistic evidence was recovered and linked to other shooting scenes.



The numbers for 2016 haven't yet been tabulated, but in 2015, "one in five shell casings from a ShotSpotter alert matched a casing from another shooting in New York City," Freer said.

The NYPD in 2009 tried, then quickly abandoned a similar program with a different vendor because the false positive rate was above 90%, Tisch said.

The program's first phase focused on the South Bronx and northern Brooklyn.

Early on, it seemed New Yorkers cared little for getting involved, with the reporting rate hovering around 20%.

In one such shooting, in March 2015, someone fired 24 times from an automatic pistol and not one person called 911.

The program has expanded twice since then and will soon be covering 60 square miles, with sensors in each borough, at a cost of about $2.5 million a year.

A GPS chip pinpoints an exact location and time, then sends the sound recording to ShotSpotter’s California headquarters, where acoustic experts determine if a gun has been fired. (Susan Watts/New York Daily News)

ShotSpotter sensors, installed in more than 90 cities around the country, are essentially laptop computers with microphones on them. In New York City, they sit atop buildings in high-crime areas.

When a shot is fired the sensors set in motion a process that takes no more than 45 seconds.

A GPS chip pinpoints an exact location and time, then sends the sound recording to ShotSpotter’s California headquarters, where acoustic experts determine if a gun has been fired — or if the sound was made by something else, such as fireworks.

If it’s gunfire, a push of a button sends the information back to the NYPD. Alerts are then sent to officers' smartphones.

Meanwhile, cops assigned to the Domain Awareness System, the department's network of data from various sources, are able, with the click of a button, to locate the police cameras near the shooting and view in real time what is happening.

Tisch said that means the immediate aftermath of many shootings — including who fired the gun — is often caught on camera.

“It happens," Tisch said. "And it happens a lot. And so, more and more, as we build out the camera network in the high crime, high shooting locations we are capturing more of the events that cause ShotSpotter activations.”