Suffolk County District Attorney Daniel F. Conley today informed Boston Fire Commissioner Roderick Fraser that prosecutors would not seek criminal charges in connection with the Jan. 9 death of Boston Fire Lieutenant Kevin M. Kelley in a Mission Hill fire truck crash.

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 – two of the “multiple, overlapping factors” in the fatal crash – should be revised to avoid future tragedies.

“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 a 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.

“A post-collision, stem-to-stern forensic examination of Ladder 26 indicated that every braking device on the truck was compromised to one degree or another at the time of the crash,” Conley wrote.

Conley said investigators considered two potential charges: manslaughter and motor vehicle homicide by negligent operation. The evidence did not support either charge because no repair or maintenance work led solely and directly to the fatal crash and the truck’s operator did not know the importance of proper air pressure within the truck’s braking system, had not been trained in emergency brake applications, and might not have been able to control the truck even with that knowledge because its air reservoir tank was so badly compromised at the time of the crash.

Another factor in the crash, Conley said, was Kelley’s instruction to the driver not to crash Ladder 26 into the cars and light poles lining the street – a decision that likely saved the lives of pedestrians on both sides of Parker Hill Avenue that day and inside the residences that might have been struck by cars or light poles displaced by a deliberate crash higher up on the hill.

Finally, the topography of Parker Hill Avenue itself played a role – had the brakes failed on almost any other street, investigators said, the operator may well have been able to control the vehicle without crashing, but the 22-ton truck only increased velocity as it travelled about 900 feet at a 13% negative grade.

Conley relayed his findings to Kelley’s family through their attorney as they requested. Conley said he would release the investigative file to Fraser and, as with all death investigations related to public agencies, would allow members of the media to review the file in the weeks to come.