Question: Who is a bestselling American writer known for his fictional and non-fictional accounts of police work in the United States, Joseph Wambaugh or Helen Zahavi?
Sentence (from "Gregory Powell (murderer)"): Infamously known as the "Onion Field" Killer, Powell's story was depicted in Joseph Wambaugh's 1973 non-fiction book, "The Onion Field".
Relevant evidence: No