HBO has released a new trailer for its upcoming six-part documentary series I'll Be Gone in the Dark, which follows the late crime writer Michelle McNamara as she hunts for the Golden State Killer. The series is based on McNamara's book of the same name, and her research was so harrowing that it kept her up night after night with terrible nightmares. Desperate to rest and quell her mounting anxieties, she accidentally overdosed on prescription drugs and died tragically in her sleep with her manuscript unfinished. After her death, McNamara's husband, comedian Patton Oswalt, enlisted his …