Former Boston Police Commissioner William Evans is a seasoned marathon veteran. Monday's Boston Marathon marks the 21st time Evans has completed the Boston race, and his 54th marathon overall.

Evans, 61, still calls South Boston home, and his neighborhood remains his primary training route. This year, he's running for the nonprofit Journey Forward, a support organization for people with paralysis. It's the second time he's run the Boston Marathon since the bombings of 2013.

Running helps to clear his head from all the violence he has seen in his 38 years with the Boston Police, Evans said. And marathon running takes the stress relief to a new level.

Evans stepped down as head of the Boston police department last August to become Boston College's executive director of public safety and chief of police. He has been asked to join the Boston Athletic Assocation's board of governors, which he calls an honor.