Tori Cannon held a portrait of her uncle, 2001 slaying victim Keyma Cannon, during the 20th Mother’s Day Walk for Peace in Boston on Sunday. At right, Jamie Hall carried Kahri Long, the 1-year-old son of her brother, Richard Long, who was killed in 2015. The procession wound through neighborhoods for nearly 7 miles, ending with passionate words on City Hall Plaza. B1.