The Boston Police Area B-3 district welcomed a new commander in late October. Capt. Sean McCarthy, who replaced Capt. John Flynn, since then has been making the rounds to introduce himself at civic association meetings, including last week’s Codman Square Neighborhood Council (CSNC).
The B-3 district encompasses the western side of Dorchester– with Washington Street as the dividing line— and all of Mattapan. He arrives at his command with crime at near-historic lows citywide, but recently trending in the wrong direction in B-3, where crime is up 15 percent through Nov. 30 compared to last year. Homicides have jumped from 4 in 2024 to 8 in 2025, and notable increases in domestic and non-domestic aggravated assaults, as well as street robberies and car thefts, have also been recorded.
Capt. Sean McCarthy, commander of the B-3 police district. Seth Daniel photo
McCarthy had been an administrative lieutenant in the downtown A-1 district for the past eight years. He started his career as a patrolman 27 years ago at the adjacent C-11 district, which encompasses most of eastern Dorchester. In his early career, he served alongside the current C-11 commander, Capt. Steve Sweeney…