SAN FRANCISCO (Map, News) - Cameras in The City have little effect in deterring crime on violent street corners, according to a new study.

Seventy-four cameras have been installed in some of the San Francisco’s most dangerous neighborhoods as city officials battle with an increasing homicide rate that was just two short of hitting triple digits last year.

Homicides within 250 feet of the cameras were eradicated. However, homicides in areas from 250 feet to 500 feet increased.

“It shows that if people are going to commit a crime they can just go around the corner from a camera to do it,” police Commissioner Joseph Alioto-Veronese said. “This system will only work if we plan on having a camera every 100 feet, which is just not realistic.”

The study, conducted by UC Berkeley and paid for by The City, showed a 22 percent decrease in property crimes within 100 feet of the cameras, but the only other nominal drop — homicides within 250 feet falling from seven cases to zero — was offset by an increase in homicides, from two to nine, in areas 250 feet to 500 feet from the cameras.

Other violent crimes studied, including assault, robbery and forcible sex offenses, showed little variation when comparing rates before and after the installation of the cameras.

“When violent crimes are lumped together, evidence shows that the cameras had little overall effect,” the report stated of the $900,000 surveillance program, which has been in place for 2½ years.

The surveillance study examined 59,706 incidents occurring within 1,000 feet of 68 crime cameras in San Francisco. The cameras were bunched in 19 locations. The study, which compared average daily crime trends from periods before and after the installation of the cameras, was a preliminary report, with more data expected to follow in the coming months.

The results did not sway the resolve of Mayor Gavin Newsom, who has advocated for 25 new cameras — at the cost of $200,000 — to join the current fleet.

“Our commitment to crime cameras is unwavering, and we remain dedicated to expanding this program,” mayoral spokesman Nathan Ballard said.

Alioto-Veronese said funding should go into improving the quality of the existing cameras so they can more clearly capture images within their range — a tool that would be effective for prosecuting criminals in court.

In 2006, the Board of Supervisors passed a resolution requiring police to give updates on crime statistics gathered from the cameras. The report was the first detailed analysis released.

wreisman@examiner.com

In brief

» Cameras: 68

» Locations: 19

» Neighborhoods: Mission, Excelsior, Western Addition, Tenderloin, Lower Haight

» Crimes studied: Larceny, burglary, motor-vehicle theft, homicide, assault, robbery, forcible sex offenses

» Biggest decrease: Larcenies within 200 feet of camera (from .031 cases a day to .023)

» Biggest increase: Assaults 200 to 400 feet from camera (from .018 cases a day to .024)

Source: UC Berkeley study