The suspected Golden State Killer is set to appear in court Friday

Joseph James De Angelo Jr was arrested in California Tuesday night on two murder charges. The now-72-year-old is suspected of being the Golden State Killer

She died in her sleep, at 46, in 2016 after a toxic mix of prescription drugs that exacerbated an undiagnosed heart condition. She wrote extensively about it in her book, I'll Be Gone in the Dark, and it was that very work that helped solve the mystery.

McNamara's book debuted as the No. 1 seller on the New York Times best-seller list.

After almost 40 years of waiting, Domingo learned Wednesday that police had arrested Joseph James DeAngelo, 72, of Citrus Heights, California, on suspicion of the slayings along with dozens of other killings, rapes and burglaries associated with the Golden State Killer in the 1970s and '80s.

"This has been quite a day", she told KTLA after news of the arrest broke Wednesday.

"For years I have been talking to her spirit and just saying, 'We're gonna get him, mom".

"And the answer is no", he said.

"In time I hope they can come to feel safe here again", he said.

Oswalt has also retweeted users who have noticed striking similarities between the book's ending and how police described McNamara was apprehended.

She and Bruce Harrington, whose brother and sister-in-law were killed in 1980 in Orange County, said DeAngelo's arrest will launch a healing process for victims that has been delayed for decades. "It was 15 years until we heard that there was a DNA sample taken from our scene", Harrington said.

Neighbour Paul Sanchietti, 58, said he was left " bone-chilled" by news that DeAngelo, who lived four houses away, had been arrested as a suspected serial killer. McNamara was also a painstaking researcher - she tracked down the tiniest of leads, be it a pair of stolen cufflinks or a water polo player whose appearance matched descriptions of the Golden State Killer, and pored over thousands of pages of old files seeking relevant information.

Police initially suspected one of Smith's business partners or Charlene's lover, but 20 years after the killings DNA evidence linked them to the Golden State murders.

"Her book and the article that lead to the book really amped up all the interest in the case, and really put a lot of focus on it", Oswalt said. I felt it on my neck.

Oswalt told the crowd that he believed the killer would be caught soon, that his time was running out.

Within hours, police in the United States announced the arrest of a 72-year-old former police officer in connection with the killings, and Oswalt praised his late wife for her persistence.

It wasn't immediately clear Wednesday whether DeAngelo was on McNamara's radar as a suspect or how much her research may have helped investigators.

"To see this book come out and have people see the handsome writer that she was, was just incredible", Skrine said. "I was on the hunt".

The use of DNA technology in DeAngelo's arrest highlights the progress that law enforcement agencies in California have done in their use of forensic science.