NEW YORK • Three days before before the wife of comedian Patton Oswalt died, she typed some notes on her laptop.
Among the looming tasks: "Find out from Debbi D about flashlight." "Find out from Ken exactly what he meant about the husband or the guy in the clown suit walking down the street."
The list catalogued potential clues she planned to chase down as she completed her book, I'll Be Gone In The Dark, an investigation into the identity of the Golden State Killer, who committed more than 50 sexual assaults and at least 10 murders in California in the 1970s and 1980s.
She never finished it. On April 21, 2016, Oswalt, 49, found her dead in the bedroom of their Los Angeles home.
An autopsy showed that Michelle McNamara, 46, had an undiagnosed heart condition and had taken a dangerous mix of prescription drugs.
The story that she spent the last five years of her life obsessively researching was half-written, the gruesome mystery still unsolved.
Oswalt could not bear the thought of her work languishing. Shortly after her death, he recruited Billy Jensen, an investigative journalist, and Paul Haynes, who worked closely with McNamara on the book as a researcher, to comb through her notes and files on her computer and piece together the story.
I'll Be Gone In The Dark, due out on Feb 27, has drawn accolades from some of the top crime and horror writers, including Stephen King, Michael Connelly, Megan Abbott and Gillian Flynn, who wrote an introduction.
It's a very ambitious book to write, about a case like this with a scope as vast as it is.
PAUL HAYNES, who worked closely with McNamara on the book, I'll Be Gone In The Dark, as a researcher
Haynes and Jensen preserved McNamara's completed chapters, which recount the killer's attacks in detail and examine his methodology, and explore her own fascination with unsolved crimes and evolution as an amateur detective.
Other chapters were pieced together from her notes and are marked with disclaimers.
Some sections read like raw, unfiltered research: One mesmerising chapter consists entirely of a transcript from McNamara's interview with Mr Paul Holes, a criminalist in the Contra Costa Sheriff's Office.
Towards the end of the book, just as McNamara's investigation seems to be gaining momentum and the killer's hazy profile begins to come into focus, it grinds to a halt.
An editor's note explains how, after she died, Haynes and Jensen were brought in to "tie up loose ends".
In that final section, the two lay out some of the avenues McNamara had planned to explore.
They describe what they found on her laptop - old maps and aerial photographs of Goleta, the site of multiple murders, images of shoe prints found at crime scenes and a spreadsheet with names and addresses of men who competed on a 1976 high school cross-country team (she thought the perpetrator might be a runner, based on victims' descriptions of his muscular legs).
They explore the potential for using DNA and genealogy databases to identify the killer's family, which McNamara believed was the best route for finding a criminal who had evaded arrest for four decades.
It took Haynes and Jensen about a year to put the book together.
"It's a very ambitious book to write, about a case like this with a scope as vast as it is," Haynes said.
"The question was, what holes should we attempt to patch?"
The research also consumed McNamara. She suffered from insomnia and anxiety.
Once, she panicked because she woke up to a scraping sound. A neighbour was dragging his trash can to the kerb in the middle of the night, Oswalt said.
Another time, when he tiptoed into their bedroom, trying not to wake her, she mistook him for an intruder and swung a lamp at his head.
She felt an obligation to solve the case and was devastated each time she developed a promising theory or zeroed in on a suspect but failed to find sufficient evidence.
Oswalt said: "She had overloaded her mind with information with very dark implications."
He was not aware of all the prescriptions she was taking. It was not until he saw the coroner's report months after her death that he realised that McNamara was coping in part by taking prescription drugs.
"It's so clear that the stress led her to make some bad choices in terms of the pharmaceuticals she was using," he said.
"She just took this stuff on and she didn't have the years of being a hardened detective to compartmentalise it."
Oswalt, who married actress Meredith Salenger last year, thinks there is a chance the killer will eventually be caught, due in part to the work McNamara did and the attention it brought to a decades-old cold case.
McNamara believed that too.
In a letter to the killer that appears at the end of I'll Be Gone In The Dark, she addresses him directly and says it is only a matter of time until police officers arrive at his door. This is how it ends for you," she writes.