When does I'll Be Gone in the Dark return?

The original six-part series premiered on June 28, 2020, on HBO, and concluded on August 2, 2020. The title of the series is taken from a threat made by the Golden State Killer during his 1976 attack upon his tenth victim, then-15-year-old Kris Pedretti, to whom he said, "Do what I say or I'll kill you and be gone in the dark".
Michelle McNamara lived a quiet life, but as her family slept, she spent the night investigating and writing a book about the Golden State Killer. McNamara hid her addiction to opioids, which ultimately contributed to her death prior to her book.