The Toronto Police Services Board will ask the city for up to $4-million to more than double the number of public CCTV cameras and install a web of microphones on rooftops that pinpoint gunshot locations and send alerts to police.

The move comes as the city grapples with a surge of gun violence that Police Chief Mark Saunders has attributed largely to gangs. Toronto has had more than 285 shooting victims so far this year, and 27 deaths. These cases pose unique challenges for police, who find that witnesses and even victims can be reluctant to speak to them. More and more, police are using technological investigative tools to fill such informational voids.

“Just like DNA changed the way police investigate crime … technology is doing much of the same,” said Michael Lacy, president of the Criminal Lawyers' Association.

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At a meeting on Thursday, the board approved a motion from Mayor John Tory, who is a member of the board, to ask council to fund the equipment. Mr. Tory said he is confident most of the money would come from federal and provincial anti-gun-violence programs.

The microphone technology, called ShotSpotter, is already being used in dozens of cities across the United States — and the company has previously lobbied Toronto. The $4-million would also cover 40 extra cameras, boosting the city’s roster from 34 to 74.

But the technology’s effectiveness has been debated. A 2016 investigation by the Center for Investigative Reporting found that out of 3,000 ShotSpotter alerts in San Francisco over two and a half years, 20 per cent sent police to the wrong location. Officers found no evidence of a shooting in two-thirds of the alerts.

The use of technology in public spaces also raises questions about potential privacy abuses.

“You do run this risk ... that, in theory, you could have videos on every street corner, you could have videos facing everyone’s house if you wanted to," Mr. Lacy noted. "And that certainly would add a layer of protection, or a valuable investigative tool — but at what cost to privacy?”

Scout Ruben of Showing Up for Racial Justice Toronto, who prefers the gender-neutral pronoun “they," noted at the police services board meeting that the motion included nothing about oversight. They expressed concerns that increased surveillance is “a really dangerous ... concerning" approach to policing gun violence.

ShotSpotter’s privacy policy notes that the devices send police a recording of only the two seconds before a gunshot and four seconds afterwards and are too high up to record private conversations. The only times a human voice has ended up on the tape, the company says, were in the rare cases when someone was yelling loudly before or after a gunshot.

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At least two ShotSpotter recordings of voices have been used to prosecute suspects in shootings, raising concerns about audio obtained without a warrant being used as evidence.

Despite questions about privacy and efficacy, some police across the United States have embraced ShotSpotter. Although at least five ended their contracts after trying it, Time magazine reports that forces in Oakland and Youngstown, Ohio, and Wilmington, N.C., credit the system with increased numbers of arrests. Gunfire in Omaha dropped 45 per cent from 2013-17, a decrease their service partly attributes to ShotSpotter.

Chief Saunders said the technology would allow police to respond more quickly to the exact location of gunshots. He insisted it would not be used to listen in on people’s conversations.

“ShotSpotter is technology that detects the sound of gunshots. Period. That’s it,” he said. He also stressed that it would be tested and scrutinized in a transparent process.

In a phone interview on Thursday, Mr. Lacy – who noted that surveillance footage can also be beneficial for accused persons at trial – cautioned that more cameras is not a “panacea.”

“Oftentimes, the images are not as clear as you’d imagine they would be," he said. “One of the risks of using video technology or any technology is misinterpreting the value of it. But sure, in some cases, will video evidence assist police perhaps in investigations where there’s a reluctance on the part of witnesses, or an absence of eyewitnesses? Certainly that’s going to be an important investigative tool.”

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Police Services Board member Frances Nunziata said people who are tired of gun violence have asked “over and over again” for more cameras on streets.

Sureya Ibrahim, who founded the support group Regent Park Mothers for Peace, sees value in cameras, particularly in gang-related cases in which witnesses do not want to come forward.

“Who is going to be putting their life in danger?” she said. “Who is going to protect those people who come out to tell [what they know]?”

Video, she said, can provide an alternate investigative avenue and could be a deterrent. For example, she said, Toronto Community Housing recently improved lighting in part of the Regent Park neighbourhood in response to residents' concerns. Part of the goal, she said, was to improve the quality of surveillance camera footage.

A more important issue than cameras is the disconnect between police and victims' families, Ms. Ibrahim said. Particularly when the victims have suspected ties to gangs, she said, there is a sense that their cases are not a priority.

“They say, ‘Oh, he’s involved.’ But what else do you want him to do when there are no opportunities?” she said. She believes the primary focus should be prevention, and providing supports for people – particularly young men – well before a crime takes place.

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The mayor has pledged his support to boosting local programming, and wants to invest $12-million in them, part of which he would like Ottawa to pay.

Mr. Tory said Thursday that that funding should also cover the additional cameras and ShotSpotter microphones. Mr. Tory said he would leave decisions about locations of the cameras up to Chief Saunders, who said only that he has "a couple ideas” about where they should go.

The motion to approve the funding for the cameras and ShotSpotter will be discussed at the city council meeting on July 23.