Once, they sent me a letter written by a retired lieutenant of the California police. The details in the letter were supposed to help clarify the chronology of the cold case investigation. The information on the timeline was useful, but what stuck in my head was done by the lieutenant aside, a complaint about disorganization and missed opportunities, about the tendency of the police to go alone and not share what they know. “Controlling policemen is like grazing cats,” the lieutenant wrote....