“There’s exhilaration, and I don’t feel it now, but I can sense that tomorrow or the next day there’s going to be a huge drop in serotonin and happiness when I realize she really isn’t here,” Mr. Oswalt said in an interview. “There were insights and angles that she could keep bringing to this case.”
“I’ll Be Gone in the Dark,” which was published in February, helped reignite public interest in the decades-old cold case. It has sold around 150,000 copies and was optioned by HBO, which is adapting it into a documentary series.
At a news conference held by law enforcement agencies to announce the arrest, an official said that the book “kept interest and tips coming in” and kept the case in the public eye, but noted that information from the book hadn’t led directly to Mr. DeAngelo’s arrest.
When Ms. McNamara died, the book was half finished. Mr. Oswalt was determined to see the project through. He hired Billy Jensen, an investigative journalist, and Paul Haynes, who worked with Ms. McNamara on the book as a researcher, to piece together the story, using her handwritten notes and the roughly 3,500 files on her computer.
The resulting book is a chilling and vivid narrative of a serial killer’s crimes, and a revealing account of Ms. McNamara’s obsession with the case and the psychological toll it took on her. It ends with a letter from Ms. McNamara to the killer, in which she predicts his eventual capture: “This is how it ends for you.”
“We have so many unsolved murders in America, and she was able to shed light on a few of them,” Mr. Jensen said.
Mr. Haynes said that after he heard a suspect had been arrested, he felt “excited, but also sad that Michelle’s not here.” Mr. DeAngelo’s name never appears in the book, and he wasn’t on their radar as a suspect, Mr. Haynes said.
“I finally had the name and the face that we’ve been seeking for seven years, the name and the face that Michelle died trying to uncover,” he said.
In a bizarre coincidence, Mr. Haynes, Mr. Jensen and Mr. Oswalt were all together at the book event in Chicago on Tuesday, and members of Ms. McNamara’s family were in the audience. A documentary film crew was shooting footage for the HBO series as the speakers speculated on how long it would take for a suspect to be caught, not realizing it had already happened.
At 4 a.m., Mr. Oswalt woke to a buzzing phone. Messages were pouring in with the news that there had probably been an arrest in the case.
Mr. Oswalt said that he hoped to visit Mr. DeAngelo and confront him with questions that Ms. McNamara planned to pose.
“It feels like the last task for Michelle, to bring him her questions at the end of her book — just to go, ‘My wife had some questions for you,’” he said.