Mayor Martin J. Walsh said Thursday that the city will begin a full-scale police body camera program, two years after officers were pushed into a yearlong pilot of the technology.
The mayor said the first phase will include the purchase of up to 400 cameras and related equipment. He offered no details on how many or which officers would wear the cameras, or when, but he noted that the city had committed $2 million in startup costs for the fiscal year that began July 1.
The city projects it will spend $8.5 million over the first three years of the program and $3.3 million in annual operating costs after that. The mayor said he is in discussions with the city’s police unions, which initially went to court to stop the pilot program, over the how to phase in the program.
Police Commissioner William Evans, discussing his last policy initiative before leaving office this week, said in an interview that the city will likely roll out the program in each of its five coverage areas one at a time.
“I think everyone has a greater appreciation for the cameras,” Evans said. “I think the public realizes it’s a good thing, and the police officers realize it’s a good thing.”
The mayor’s announcement coincided with the long-awaited release Thursday of a final report on the yearlong pilot. Confirming the conclusions of an initial analysis released earlier this year, the report found that the number of complaints against officers who used the cameras, as well as the officers’ reported use of excessive force, dropped slightly — what the mayor called in a statement “small but meaningful benefits” for residents and police officers.
The final report, which also examined the nature of police officers’ interaction with residents, said the placement of cameras on officers did not alter their regular work activities or reduce their productivity. The report said there was no notable difference in the number of dispatched calls received, officer-initiated calls, crime incident reports completed, arrests made, or Field Interrogation and Observation reports, which include incidents in which an officer stops someone based on a suspicion.
The report also found no difference in the racial or ethnic backgrounds of civilians targeted in Field Interrogation and Observation reports when officers wore cameras.
“The vast majority of community members and members of advocacy groups interviewed in this study supported expanding the body worn camera pilot to a citywide program,” wrote the report’s authors, Anthony Braga and Jack McDevitt, of Northeastern University.
“This study shows the potential value that body cameras can have as part of our overall strategy for strengthening ties between law enforcement and the residents they serve,” Walsh said in a statement.
City Council President Andrea Campbell, who had pushed for a body camera program, also praised the announcement.
“I’m grateful to [Boston police] and Northeastern for thoroughly reviewing the pilot program, and to the mayor for committing money to implement a permanent body camera program, a technology that not only serves our officers but also the community, and has real potential to build more trust between the two,” she said.
The announcement comes amid a swell of support for police cameras in many major cities, and following several high-profile incidents of questionable police tactics recorded on video, including fatal shootings of unarmed men by officers.
In February in Boston, officer Zachary Crossen was criticized by civil rights groups when he was recorded in a hostile confrontation with a young man who did not commit a crime. The department disclosed in March that Crossen had participated in the pilot program, but he had not been wearing his camera at the time because the program had ended.
Evans said that video can help justify police actions, such as in 2015, when a fast food restaurant surveillance camera captured the shooting of a suspected ISIS supporter who allegedly approached officers with a military-style knife.
The one-year pilot program in Boston, which began in September 2016, placed 100 cameras on patrol officers in five police districts, as well as plainclothes officers in the Youth Violence Strike Force, which focuses on gang members. In the study, the work of the roughly 140 officers who wore cameras at different times was compared with a similar group who did not wear cameras.
The review of the program, which produced roughly 38,200 recordings covering more than 4,600 hours of police activity, found that the number of complaints against officers who wore cameras dropped by roughly one a month. There were nine fewer use of force reports — an officer’s self-initiated report that force was used during an incident — or slightly less than one per month.
The report’s authors found that the difference was recognizable but minimal, because Boston already has a low rate of complaints. From 2013 to 2017, for instance, the number of complaints against officers decreased 46 percent, from 350 complaints in 2013 to 189. Meantime, use of force reports filed by officers decreased by 52 percent, from 107 reports in 2014 to 51 in 2017.
William Gross, the superintendent in chief who is slated to be sworn in Monday to succeed Evans as commissioner, said he supports the program, saying the pilot study was “very important in understanding firsthand what members of the community believe will help the city move forward and how technology can play a role.”
The head of the union that represents police patrol officers did not respond to a request for comment. The union had initially sought a court ruling seeking to halt the forced implementation of the program, but a judge refused the request.
Evans said officers have since opened up to the program.
“We have nothing to hide,” he said on Thursday. “These cameras will only help justify what we do every day, and that’s good police work.”
Milton J. Valencia can be reached at milton.valencia
@globe.com. Follow him on Twitter @miltonvalencia.