The bullets that pierced a 22-year-old Roosevelt man’s chest at a West Greenwich Avenue house party rang out in the early Saturday morning hours of July, 26, 2009. Normally, police would not have arrived until after someone called 911, but this time, officers were on the scene prior to the call three minutes later.

A Nassau County police officer gives a demonstration of the Shot Spotter gunshot detection system.

Police credit the speedy response that saved the victim’s life to Shot Spotter, a GPS system that maps gunfire within seconds, which last summer targeted this neighborhood and Uniondale–part of what Nassau police call the “gun corridor.” Commissioner Lawrence Mulvey admitted that the technology’s deterrence value is difficult to gauge, but he believes the lives it has saved is worth its expansion into a third high-crime neighborhood: Lakeview. Meanwhile in Suffolk, the system was caught in a crossfire between lawmakers debating its cost effectiveness for Huntington Station, where violence prompted school officials to close an elementary school in July.

“That young man may not have survived had Shot Spotter not been installed,” Mulvey said of the house party shooting victim during a recent press conference where he highlighted cases that the system aided. The crowd could be heard screaming in horror prior to the gunshots in a playback of the audio recording.

On laptops in patrol cars linked up with Shot Spotter, shooting scene maps appear within three seconds for officers in the First Precinct, which covers Roosevelt and Uniondale. The tool also provides responding officers with “situational awareness” because Shot Spotter triangulates within several feet down to which side of a building shots have been fired from–a huge tactical advantage, Mulvey said.

Increased response time and lifesaving function aside, the biggest selling point may be that it is paid for through asset-forfeiture funds–money seized from criminals, meaning no taxpayer expense. That is why perennially cash-strapped Nassau officials are in talks with Lakeview community leaders to bring the technology there by the end of the year.

“It’s easier to expand the technology now that we have the infrastructure on place,” said Second Deputy Commissioner William Flanagan. A Nassau police spokesman said the system has been activated about 600 times in the past year.

Shot Spotter has sparked the interest of Suffolk County Legis. John Cooper (D-Lloyd Harbor), whose district includes the Huntington Station neighborhood where school officials closed the Jack Abrams Intermediate School after a string of shootings nearby. Suffolk police last month assigned an added patrol car to the area because gun violence continues to plague the blocks surrounding the school.

“We’ve already proven how useful it is to have automatic ‘eyes’ covering our crime-prone areas,” Cooper said, alluding to surveillance cameras that have been installed in the neighborhood. “Now we’ll have ‘ears’ to hear where the crime is coming from as well.”

Suffolk County Executive Steve Levy said he will keep an open mind, but is not convinced. “Initial analysis indicates that the technology is not as effective in suburban areas as it is in more urbanized, condensed areas,” he said in a statement. “There is no empirical evidence to suggest that it is effective as a deterrent or that it has helped lead to faster apprehension of suspects. To expend financial resources on a technology that doesn’t deter gun violence is taking money away other methods.”

Although there is no way to prove how much crime has been deterred by any police tactic, Mulvey is a believer in this technology.

“The Shot Spotter system is not designed to make arrests, its designed to change behavior,” Mulvey said, adding that gang members his detectives have interviewed have made it known that they are aware there are microphones hidden in their hamlet. Installation “doesn’t meant your going to solve crime if you don’t have assets on the ground who can get there in a minute or less.”