ANALYSIS/OPINION: A seemingly unrelated criminal case in Washington has reopened a popular Trump-Russia guessing game: Who is Joseph Mifsud? The FBI says the vanishing professor is a Russian spy. Trump backers, citing Mr. Mifsud’s extensive Western intelligence contacts, suspect he’s an FBI, CIA or MI6 plant. The Washington Times examined Mr. Mifsud’s extensive resume and frequent travels, revealing a skilled networker far more wedded to the West than the East. In May 2017, 10 months into the FBI Russia conspiracy probe, Mr. Mifsud spoke in Riyadh at a high-powered terrorism conference. On his panel was counterterrorism expert Michael Hurley, who...