CHARLOTTE, N.C. -- Charlotte police are moving forward with plans for enhanced digital surveillance of the city’s streets and residents, touting new camera and audio networks as modern tools that help investigators catch bad guys.
But interviews with researchers and police in other cities suggest that while there are clear benefits, police officials have to be wary of technical glitches that trick surveillance microphones and cameras, such as firecrackers that sound like gunshots or blurry video that leads observers to jump to conclusions.
Perhaps more importantly, those officials say, police have to be meticulous and transparent in developing guidelines for using these surveillance systems if they want residents to see them as protectors, rather than invaders of privacy.
“These devices are not designed to replace good, old-fashioned police officers,” said Anthony Guglielmi, spokesman for the Baltimore Police Department.
“They’re designed to augment police officers; you have to learn how to maximize their effectiveness.”
The questions have risen as the Charlotte-Mecklenburg Police Department seeks to expand its use of video cameras and specialized microphones around the city.
Police began using the ShotSpotter audio detection system in August, focusing on 2 square miles in the center city as they ramped up security for the Democratic National Convention.
ShotSpotter uses a network of microphones to triangulate loud bangs of gunfire, quickly sending officers to potential shooting scenes even if no one dials 911.
Officials were pleased enough with the system to begin plans for expansion, identifying six areas they believe may benefit from ShotSpotter, based on reports of gunfire and violent crime. Police briefed Charlotte City Council members Monday about their digital surveillance plans, but didn’t specify the six new ShotSpotter locations.
“We just now feel comfortable with the way that system works, and it has proven very reliable to us,” Deputy Chief Harold Medlock told council members.
But the system is not infallible. Gunshots are not the only things that can make the loud, percussive sounds the microphones hear. In the past, other cities’ systems have been triggered by cars backfiring or a whirring helicopter.
“If you really look hard at it, you have to weigh how many false positives do you want to chase,” said Peter Scharf, a criminologist at Tulane University.
He and other criminologists said the results of the system have been mixed.
In Baltimore, police partnered with Johns Hopkins University several years ago to test an early version of gunshot-detection technology developed by the university. But the system wasn’t accurately detecting gunshots, Guglielmi said, and the effort was abandoned.
ShotSpotter has been through several iterations. Its earliest versions required police to analyze the gunshot sounds themselves. The latest version – the one CMPD has bought into – hooks the department up to a call center. A person there analyzes the sound and determines if it’s a legitimate gunshot, then notifies police dispatchers. The updated version has more police departments around the country looking into investing in the system.
Sean Baldwin, police chief in Fort Pierce, Fla., said his department is thoroughly researching the technology and has heard good reports from other Florida agencies that use ShotSpotter. Still, Baldwin is cautious about the system. He wants to ensure it doesn’t constantly put out false alarms. That’s dangerous, he says.
“You want officers to respond to it like it’s a crime in progress,” Baldwin said. But if only a small percentage turn out to be real emergencies, “I fear that officers can get a little nonchalant in their responses and that could pose a safety risk.”
On one recent Saturday afternoon, ShotSpotter alerted a Charlotte police dispatcher at 3:42 p.m. to “one round of possible gunfire” at the corner of a building in uptown’s Third Ward.
Minutes later, two officers circled the block slowly in their patrol cars. They craned their necks to see into windows and parking lots, and kept their windows rolled down to listen for cries of trouble.
There were none – or at least none that were immediately obvious – so, just before 4 p.m., the officers went back to patrolling.
As far as they could tell, the ShotSpotter call was a false alarm.
Surveillance evidence in court
So far, prosecutors at the Mecklenburg County District Attorney’s Office say the ShotSpotter microphones and the camera network haven’t given rise to courtroom debates over individual privacy rights.
The office’s homicide team often pulls surveillance video from convenience stores or hotels, but Assistant District Attorney Bill Stetzer said he can’t remember a recent case with evidence from one of the cameras watched by CMPD.
Lead property crime prosecutor Glenn Cole said the same thing.
In Baltimore, where an elaborate network of surveillance cameras has been in place since the early 2000s, prosecutors have long relied on video pulled from that system. Video evidence has made it easier for Baltimore prosecutors to obtain guilty pleas before trial and convince juries to convict afterward, said Elizabeth Embry, a deputy state’s attorney for Baltimore City.
She pointed to a recent case where surveillance video caught a fight on tape, followed it down a city street and captured a stabbing on video.
Baltimore’s defense attorneys haven’t used privacy questions as a tactic in criminal cases, Embry said, because the videos capture only public places. Moreover, city residents have come to expect surveillance as a sort of standard of protection, Baltimore officials said.
“Today, I don’t see a lot of people worried about it,” said Doug Ward, director of public safety leadership at Johns Hopkins University and a former Maryland State Police major. “As crimes are solved and people get used to the fact that we’re being watched on Internet use and under surveillance in every store we go, we’re giving up some of that expectation of privacy.
“Do you trust that it won’t be abused? That’s the question.”
Clear, open policies
Just as it remains to be seen exactly how ShotSpotter will be put to use and how effective it is, Charlotte police are also in the midst of developing guidelines for monitoring some 650 cameras spread throughout the city.
Officials are working within the department to determine where those cameras, concentrated uptown during the DNC, should be moved, how long video footage should be stored and how to monitor the people who watch the cameras.
One thing that’s absolutely clear, deputy chief Medlock said: Those cameras, whether owned by the city or by private companies, will be focused only on public streets and intersections.
Officials from other cities say when creating surveillance policies, the details are important.
Baltimore, for instance, has been highlighted in a recent study by the Urban Institute for its effective use of surveillance video.
The surveillance of some 500 of the city’s downtown cameras is overseen by a group of people trained to monitor the feeds, Guglielmi said. These monitors work closely with 911 dispatchers, focusing cameras on areas where crimes are occurring, but they also watch for suspicious activity.
Because Baltimore officials have been open about which cameras are watching and when, residents have complained very little about the surveillance, according to Ward, the Johns Hopkins professor.
“Particularly in Baltimore, they celebrate those cases that work,” Ward said. “It’s not secretive; if you make it secretive, people tend to distrust that.”
Baltimore police have had neighborhood groups and community watch organizations purchase video cameras and ask police to monitor their feeds, too, Guglielmi said.
“It’s truly a force multiplier for the Baltimore Police Department,” Guglielmi said.