Unfortunately, McNamara passed away on April 21, 2016 at age 46 due to a deadly combination of prescription drugs in her system and an undiagnosed heart issue — mostly likely, Oswalt told the New York Times, because she was using the pills to cope with the difficult details of the Golden State Killer case. I’ll Be Gone In The Dark was published posthumously in 2018 and with the help of Oswalt, McNamara’s researcher Haynes, and crime writer Billy Jensen. The book was a surefire hit, so much so that HBO bought the rights before it was published to start on a documentary as soon as possible. In an interview with Refinery29, Liz Garbus , who directed the documentary, said of McNamara, “I admire so many things about her, but really, just as a writer, she was such an incredible wordsmith and she so vividly brought these scenes alive that I’m just floored by her.”