Interim DA Kevin Hayden’s campaign said they won on Tuesday a bitter Democratic primary against Hyde Park Councillor Ricardo Arroyo for Suffolk County district attorney, prevailing after weeks of backbiting and vicious volleys that spilled into other Boston political arenas and eroded public trust in the office.

The result ends a pitched battle for the seat, rocked by separate reports in the Boston Globe that alleged Hayden mishandled an investigation of Transit Police officers involved in a Mattapan roadway incident while Arroyo was investigated for sexual assault as a teenager.

Hayden and Arroyo denied the respective accusations and ignored ensuing calls to resign. Arroyo faced a collapse in political support, as Mayor Michelle Wu and Sen. Elizabeth Warren pulled their endorsements.

The back and forth over the Arroyo assault allegations hit the City Council last week, with Hayden and Arroyo supporters clashing over court documents. Arroyo went to court to obtain the documents, and argued they cleared him of the allegations.

Gov. Charlie Baker appointed Hayden, a Roslindale resident, as interim DA after Rachael Rollins left for the US Attorney’s Office, and Hayden ran to serve a full term.

Before the appointment, Hayden served for six years as chairman of the state’s Sex Offender Registry Board. His resume also includes stints as a criminal defense attorney and a Suffolk County assistant district attorney.

Arroyo, a district city councillor from Hyde Park, is the son of Register of Probate Felix D. Arroyo. First elected in 2019, Councillor Arroyo previously worked as a public defender for the Committee for Public Counsel Services.