Among those killed by the Taliban in recent months: Mr. Rahmatullah's father, brother, cousin and uncle.

WSJ: Once-Touted Afghan Force Falls on Hard Times

In an interview, Deputy Attorney General Rahmatullah Nazari said prosecutors didn't charge Mr. Azimi because they lacked evidence.

WSJ: In Afghanistan, Prosecution of 'Malign Actors' Stalls

Mr. Rahmatullah, 33 years old, has been injured, too, and his family's house in the district has been torched.

WSJ: Once-Touted Afghan Force Falls on Hard Times