FX has released a trailer for The Most Dangerous Animal of All, the network's first true-crime docu-series that dives into one man's possible shocking connection to history's most famous cold case. The four-part series is based on the book by Gary L. Stewart, whose search for the father he never knew led him to believe he might be the son of the notorious Zodiac killer. This is a...genuinely insane story, and almost impossible to believe in that way most true-crime seems impossible to believe. I mean, this FX series isn't about …