John Cook is leaving Yahoo. Here's why you should care. Cook is a former Chicago Tribune reporter who specializes in digging up documents. He decamped for Gawker, and had some success marrying his investigative approach to Gawker's gossipy style. After Freddie Mac's acting chief financial officer committed suicide, for instance, Cook obtained evidence that investigators were looking into whether agency officials had concealed or misrepresented information related to the banking bailout. (The probe apparently went nowhere.) In April, as Yahoo was hiring a number of mainstream journalists for its newsy Upshot blog, Cook signed on. But the relationship went sour.