Karmen Bailey Walker didn't know yet about the traffic stop or the gunfire, but she knew in her gut the gravity of what she was seeing: Prince George's County police cruisers streaming past her on the highway.
A phone call confirmed what she dreaded most: An officer had been shot.
It was June 21, 2005 — 19 months after Walker's own husband, a Prince George's police corporal, died in an auto accident. Now she found herself racing to the hospital where another officer, Steven Gaughan, was taken after being mortally wounded following an attempted traffic stop.
"What I tried to do after my loss was to reach back and help the next family get through," she...