Substance abuse has been the "common denominator" in a string of recent Madison robberies, including the armed robbery Wednesday that left a Sun Prairie man dead, a police captain said Sunday night at a neighborhood meeting.

Four days after Gregory J. Bickford, 26 - suspected of robbing Cousins Subs several blocks away - was shot and killed by a Madison police officer on the South Side, city officials told South Side residents at the meeting that their neighborhood is no less safe than anywhere else in the city.

Capt. Joe Balles, commander of the department's South District, said crime in the district for the first six months of this year was down 15 percent from the same period in 2008. In the city as a whole, crime is also down, said Joel Plant, an aide to Mayor Dave Cieslewicz.

What has increased, Balles said, is heroin as a motivation for robbery. Bickford, like several suspects involved in robberies in the last few weeks, was known to use heroin, he said.

"They're just trying to get their next fix," Balles said.

Police believe that just before 5 p.m. on Wednesday, Bickford robbed the Cousins Subs at 1124 S. Park Street before walking about four blocks to the corner of Lakeside and Whittier streets. He was shot by officer David Retlick after he pointed a loaded .22 caliber revolver at Retlick, police said.

Balles could not say whether Bickford had heroin in his system at the time of the robbery.

"It seems to be a far more acceptable drug than it was maybe 15, 20 years ago," he said. "I'm sure we're not even scratching the tip of the iceberg and it kind of scares me."

Other recent Madison robberies possibly motivated by heroin use include those of Greenbush Bakery, Topper's Pizza and Jimmy John's on the Near West Side,police said.

Ald. Julia Kerr, whose 13th District includes the location of the shooting, said she doesn't want a "handful of people making some very bad decisions" to affect how other residents live their lives.

"This neighborhood really is very safe," she said.