The more than 300 video surveillance cameras positioned around Baltimore has been a source of constant debate between city police and prosecutors. Now, a new report from the University of California, Berkeley on cameras in San Francisco cast doubt on their usefullness, at least as far as deterring violence crime. Above is a photograph taken by Baltimore Sun photographer Glenn Fawcett at a fatal shooting Jan. 9 on East Lombard Street.

Researchers concluded that the cameras did little to prevent murders, drug dealing and prostitution, but did help prevent property crime. The report also says that in court, the videos don't always provide conclusive evidence of guilt.

What I think from reading the 180-page report and reviewing statistics and cases in Baltimore is that the surveillance cameras help, but do not replace, good old-fashioned police work. Yes, cops love to release videos showing crimes, and we call watch and are horrified. But it's often hard to identify an acutal suspect from the video, and more often than not, only a part or the aftermath of a crime is caught on the tape.

That leaves attorneys to argue and jurors to decide what actually happened. In one case city prosecutors described to me, a witness testified to being one place on the street when the video clearly showed her standing someplace else when she saw one man shoot two other men. Defense attorneys seized on this to question her integrity, but did convict in the end.

One interesting point in the report is that prosecutors in San Francisco complained that cops put up the cameras but didn't consult them. That's important because the tapes, like bullet casings and other evidence, has to stay in what is called a "chain of custody" to ensure it's integrity once it arrives in the courtroom. Prosecutors in Baltimore complained several years ago that police didn't sit down with them to discuss how the tapes would be used and in what way.

"When the cameras were announced by then Mayor O'Malley and brought into the city, no one consulted with our office on how to use the cameras effectively to bolster prosecutions," Margaret T. Burns, the spokeswoman for the city State's Attorney's Office, told me. "They were viewed by the administration at the time as a quick fix to violent crime."

Cooperation has improved, but Burns said questions remain. She said community members continue to tell State's Attorney Patricia C. Jessamy, "We would just like another police officer."

Added Burns: "Our preliminary results are similiar to the preliminary results in San Francisco. The cameras are not always relevant to the violent crime that is being prosecuted. They are helpful investigative tools. The footage is often used to point us in the right direction. Whether or not they have an overall affect on violent crime in the city, whether or not they are cost effective, are things we can't speak to, but they are questions that have been raised."

Burns said the cameras are catching a lot of nuisance crimes, such as people smoking marijuana, leading to arrests that she says "are being thrown out at a high rate." She added, "I think the jury is still out. I think the public wants some conclusions. They tell us, 'Rather than a blue box, we'd like Officer Friendly on the street. We do hear that often."

The problem isn't in what the cameras do or don't do, but how the program was sold. We love to tout new toys, especially expensive ones, and the city police surveillance program was initially sold to us as a way to prevent crime, keep people safe and help put bad guys in prison. The report shows that in San Francisco, the cameras don't prevent violent crime and witnesses and cops are still need to put criminals away.

There is a middle ground here. The cameras won't prevent or solve everything, but they will help cops and prosecutors with their cases. The Urban Institute is studying Baltimore's program and says a report could be out by March. I'm anxious to see what it says and whether they reached the same conclusions as out west.

Sheryl Goldstein from the Baltimore mayor's Office of Criminal Justice, told me that what is unique about Baltimore's camera system is police officers are often watching streets in real time and can quickly direct their colleagues to crime scenes. She read parts of the San Francisco report and sent me this response:

The report highlights issues with technology and stakeholder relations. Baltimore has made significant progress improving technology and building the relationship with the State's Attorney's Office which has increased the efficacy of the camera program. We continue to build on those areas. In addition, Baltimore's live monitoring has made the cameras an effective tool to engage in targeted enforcement and to capture and sometimes even prevent violent crimes in progress. I think the San Francisco study says that camera footage was only used to help solve or prosecute 5 or 6 cases of violent crime since 2005.  Baltimore has been far more progressive in that area.