Back in April of 2016, author Michelle McNamara passed away unexpectedly at the age of 42.

Though perhaps best known to the general public as the wife of comedian Patton Oswalt, McNamara was a highly-regarded true crime writer who was hard at work on her magnum opus at the time of her death.

I’ll Be Gone in the Dark became an instant bestseller when it was published posthumously in February of this year, and now it looks as though the book may have helped lead police to a serial killer and rapist who evaded capture for more than four decades.

Former police officer Joseph James DeAngelo, 72, was arrested in Sacramento this morning on two counts of murder.

There’s reason to believe that DeAngelo might be the man police referred to as the East Area Rapist and who McNamara dubbed the Golden State Killer – an elusive suspect whose DNA ties him to 12 murders, 45 sexual assaults, and 120 burglaries committed between 1976 and 1986.

The investigation has been referred to by Sacramento County District Attorney Anne Marie Schubert as “the most prolific unsolved serial killing case probably in modern history.”

At the time of her death, McNamara’s manuscript was left unfinished.

The published version has been supplemented with material from researcher Paul Haynes and journalist Billy Jensen as well as an afterword by Oswalt, all of whom took to social media today to celebrate what appears to be the completion of McNamara’s life’s work.

“Think you got him, Michelle,” Oswalt said in an emotional video posted to Instagram this morning.

The famed comic will also produce an upcoming HBO docudrama about the GSK investigation.

The publicity surrounding the book and HBO special is believed to have prompted Sacramento police to re-open the 32-year-old cold case.

Interestingly, when news of DeAngelo’s arrest broke, Oswalt was with the book’s research team at a press event in McNamara’s hometown of Chicago last night, which also served as the first night of filming for the HBO documentary.

“Ended with me saying, ‘He’s running out of time.’ And now all of this. Surreal,” Oswalt tweeted today.

Many fans of McNamara’s work have posted some of the more eerily prescient passages of her first and last book, particularly a section in which she addresses the killer directly, imagining him being apprehended as an old man.

“You’re long past leaping over a fence. Take one of your hyper, gulping breaths. Clench your teeth. Inch timidly toward the insistent bell,” McNamara writes.

“This is how it ends for you … Open the door. Show us your face. Walk into the light.”

While there are certainly no happy endings in a story this macabre, we hope that DeAngelo’s arrest can bring a modicum of relief to those who were tormented by his crimes – as well as the family of the woman who devoted her final days to seeing him brought to justice.

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