Surveillance cameras may help police with criminal investigations but wouldn't prevent crimes by themselves, according to one surveillance expert.

Josh Greenberg, a mass communications professor at Carleton University, who has studied the impact of closed circuit television (CCTV) surveillance, says people support the idea because they believe it will help protect them from robberies, sexual assault or other violent crimes.

"The belief is that cameras would allow police to prevent these crimes from happening because they would get there in time," says Greenberg. "But there is no empirical evidence, from all the research I looked at, that shows that the kinds of crimes people are most afraid of are deterred by the presence of video cameras."

In Britain, which has more CCTV cameras per citizen than anywhere else in the world, Scotland Yard says a huge investment in surveillance cameras has not had an impact on the crime rate. For example, only three per cent of street thefts in London were solved using CCTV images, The Guardian newspaper reported a senior police official as saying.

The cameras are very effective in preventing property crimes, says Greenberg. But their presence in neighbourhoods such as Centretown would only help the police gather information and catch suspects after a crime took place, he says.

The controversial cameras have long been mooted for Ottawa. The issue was raised again at the end of last month when police chief Vernon White said CCTV cameras are useful tools and there should be more in the city, but that the police can’t pay for them.

The 2007 crime report recently released by police showed that the overall crime rate in Ottawa decreased by six per cent since last year, but the number of assaults grew by five per cent.

Stephanie Strudwick, a member of the Central Ottawa Neighbourhoods Safety Alliance, has been supporting the idea of police-monitored cameras since 2006, using the City of Hamilton as an example.

The alliance includes members from various safety committees and community groups and represents the Somerset, Rideau-Vanier and Kitchissippi wards.

Strudwick says the major problem in Centretown for the last three years has been drug users.

"Whenever you have people using drugs . . . you also have increases in certain types of unsavoury behaviour," says Strudwick.

She says cameras should be installed especially at the Rideau Centre and at the intersection of Bank and Somerset.

The presence of cameras, she says, would have a psychological effect that would deter crime. "These people, they know they’re up to no good, so if they know they’re being watched, they are not going to do it."

But the idea of surveillance cameras also raises privacy concerns for some residents.

According to the guidelines of the federal privacy commissioner, video surveillance should be used only as a last resort and only after the public has been consulted.

Greenberg says a rigorous public consultation is necessary for people to understand the core of the issue. Influential figures such as the police chief shouldn’t have been advocating for the policy before residents got a chance to express their views.

"Let’s have a full open airing of the debate and do so in a way that’s respectful and meaningful," Greenberg says. "That would make me more comfortable."

Mohsen Mohammadi, who owns a grocery store on Gladstone Avenue, says cameras might help to catch robbers but they wouldn’t help much with tackling prostitution, a major concern in the area.

Police cars regularly patrol Gladstone but the number of prostitutes has not decreased, Mohammadi says. Cameras wouldn’t do a better job, he says.

Somerset Coun. Diane Holmes says the idea of CCTV cameras is worth investigation.

"I would be interested in hearing what many of the people who live and work downtown feel about this, and the businesses as well," says Holmes.

But, she says, City Council has yet to tackle the issue.