BOSTON - Suffolk County District Attorney Daniel Conley announced Dec. 10 that training and maintenance were two of the "multiple, overlapping factors" in the fatal crash that killed Boston Fire Lieutenant Kevin Kelley on Jan. 9.

After an 11-month probe by Boston Police homicide detectives, renowned experts in the field of forensic motor vehicle examinations, and Suffolk County attorneys specializing in the investigation and prosecution of motor vehicle-related offenses, Conley said that no person or entity bore criminal responsibility for Kelley's death, but recommended that training and maintenance should be revised to avoid future tragedies.

In a letter to Boston Fire Commissioner Roderick Fraser, Conley said prosecutors would not seek criminal charges in connection with Kelley's death in the Mission Hill fire truck crash.

"Human error, insufficient driver training, the substandard in-house and outside maintenance of Ladder 26, the topography of Parker Hill Avenue, and Lieutenant Kelley's self-sacrificing determination to protect civilian lives all combined on that fateful day to send a massive piece of firefighting machinery hurtling toward a tragedy that is still felt almost a year later," Conley wrote in the letter to Fraser.

Kelley, a 30-year veteran of the Boston Fire Department, died of blunt force traumatic injuries when Ladder 26 lost braking power during its descent of Parker Hill Avenue and crashed into a Huntington Avenue building. At the time, Ladder 26 had been operating for years with a compromised braking system as a result of poor maintenance. Moreover, the firefighter behind the wheel that day had not been properly trained in the use of the 22-ton truck's air brakes or emergency retarding system.

Read the D.A.'s full statement and letter to Boston Fire Department Commissioner Roderick Fraser.

Following the fatal crash in January, the Boston Fire Department hired a new fleet manager and safety officer in late April to manage the department's fleet. The safety officer was reportedly fired less than two weeks into the job for absenteeism.