[Read a transcript of Part 1 of the series.]

As soon as I heard Davetta Parker’s voice, I knew I had to meet her. Her grandson Lavar Montray Douglas, known as Nook , was among seven young people from one high school in Baltimore who were killed in the spasm of violence that shook the city after the death of Freddie Gray, a 25-year-old black man who died of a severe spinal cord injury while in police custody.

I cold-called her. She was sitting at her desk in a Baltimore public library. She said, “I think God sent you to me.” She said that she had so many questions about the death of her grandson, who had been shot by a police officer, and that she needed someone to help investigate, because the police never did. She said that she had written letters to news channels and newspapers, but that no one had written back. And there I was on the phone.