Homicides reached a 10-year low in 2015. Why?

Boston police closed off a scene with crime tape in January 2015.David L. Ryan/Globe Staff/File/Globe Staff

The number of homicides in Massachusetts reached a 10-year low last year, and officials attribute the decline to focused attention on gang violence, drugs, and gun trafficking.

Some also credit last winter’s epic snowstorms, which kept people off the streets.

Overall, there were 133 homicides in Massachusetts in 2015, down from 146 in 2014, according to figures provided to the Globe by the State Police and departments in Boston, Worcester, Springfield, and Pittsfield.

The annual number has been falling since 2010 — when there were 220 homicides statewide — and mirrors a national downward trend.

The reason for the decline in 2015, according to the State Police, was the focusing of resources to “hammer the drug and gun trade in high-crime areas,” said State Police spokesman David Procopio.

The State Police investigate homicides across the state, except in Boston, Worcester, Springfield, and Pittsfield, which conduct their own investigations.

“Our State Police gang units and drug units make great efforts in urban neighborhoods, working with their local police counterparts, to disrupt drug networks and seize illegally owned guns and arrest the people who sell the drugs and the guns,” Procopio said.

Boston Police Commissioner William B. Evans pointed to youth outreach programs, community walks, and initiatives aimed at seizing illegal guns as contributing factors to fewer killings in Boston.

“I’m hoping we have as much success this year as we did last year,” Evans said. “These small measures have had some impact to set the tone.”

Suffolk County District Attorney Daniel F. Conley said Boston accounts for one out of every two of the state’s homicides. The downward trend, he said, is the result of smarter crime-fighting strategies that target “violent offenders” and prevention programs that steer juveniles away from the criminal justice system.

“You have to strike the right balance,” Conley said.

In Boston, homicides dropped to 39 from 53 in 2014.

The homicide figures alone, however, don’t tell the whole story, said Frank Farrow, community engagement coordinator for the TenPoint Coalition. He pointed to the fact that although deaths from gunfire dropped, overall shootings were up.

There were 244 nonfatal shooting victims in Boston in 2015 compared with 214 the year before, according to police data.

“I don’t think those are stats that people can pat themselves on the back about,” said Farrow. “Every shooting is a potential homicide.”

Farrow said Boston’s top-notch medical care has helped save shooting victims.

Killings were up in each of the other three cities that investigate their own homicides. Springfield had 18 homicides in 2015, an increase of four from the previous year. There were eight homicides in Worcester, compared with seven in 2014; and Pittsfield had four homicides in 2015 compared with none the year before.

Last year there were no homicides in Hampshire, Franklin, and Berkshire counties, according to the State Police records.

The statewide clearance rate for solving homicides increased to 71 percent last year, up from 62 percent in 2014, data show. The figure does not include clearance rates for Pittsfield.

Farrow said investments in prevention could drive the homicide rate down further and better police-community relationships could increase clearance rates.

The ability to track crime in real time, an increase in video surveillance, changes in the drug market, and an aging population have contributed to the nationwide drop, said James Alan Fox, a criminology professor at Northeastern University.

But Fox warned that murder rates can rebound, noting that homicides increased in the early 1990s during the crack cocaine epidemic.

“You don’t solve the crime problem; you only control it,” he said.

Because of that, Fox said, declining homicides should not result in funding cuts to programs that have led to the state’s success.

Seventy percent of all homicides are the result of gun violence, said Stephanie Hartwell, professor of sociology at the University of Massachusetts, who lauded Boston police for using gang sweeps as a crime prevention tool.

Plymouth County District Attorney Timothy J. Cruz said authorities use sweeps to target drug-infested neighborhoods “to let people know we’re watching. We’re targeting the individuals dealing the drugs as opposed to individuals using them.”

He said such programs as Operation Safe Streets allow law enforcement agencies to meet with community members about public safety issues in their neighborhood.

Homicide rates are cyclical and dependent on several factors including a shift in demographics and the incarceration of members of street gangs and violent felons, officials say.

Homicides and shootings in Boston surged in the early 2000s in part because “many of the ‘impact players’ who went to prison in the 1990s were getting released and returning to their old stomping grounds,” Procopio said.

One of the factors that some believe played a role in the decline is beyond the control of law enforcement: last year’s record-breaking snowfall.

“Bad weather keeps people indoors, not just the potential victim, but potential offenders,” said Fox.

Chelsea Police Chief Brian Kyes said, “the snow slowed everything down.”