The Golden State Killer terrorized California in the '70s and '80s. HBO's new series 'I'll Be Gone in the Dark' looks at how one woman helped unravel the mystery.

• HBO's latest docuseries "I'll Be Gone in the Dark" will premiere on Sunday.
• The show focuses on late crime writer Michelle McNamara and her quest to find the Golden State Killer.
• McNamara is the author of the true-crime book "I'll Be Gone in the Dark." She died before it was published in 2018.
• The Golden State Killer is believed to be responsible for at least 13 murders and over 50 sexual assaults in '70s and '80s California.
• McNamara's work with investigators helped bring the case to light.
• "I'll Be Gone in the Dark" also focuses on a potential suspect in the rapes and murders — Joseph DeAngelo, who was arrested by law enforcement in 2018 after DNA reportedly linked him to the crimes.

Little was known about the so-called Golden State Killer until very recently.

The criminal, who was also dubbed the East Area Rapist, the Original Night Stalker, and the Visalia Ransacker, is believed to have killed at least 13 people and raped over 50 others in '70s and '80s California.

But until Michelle McNamara's landmark book "I'll Be Gone in the Dark" was published in 2018, the Golden State Killer (a moniker McNamara gave him) wasn't widely known to the general public.

McNamara died before the publication of her book, but a new documentary from HBO, also titled "I'll Be Gone in the Dark," brings new attention to her work and includes several major developments in the case.

Here's everything you need to know about the documentary, the Golden State Killer, and the quest to track him down.

The Golden State Killer was a murderer and rapist who terrorized Californian towns for over a decade

Crimes later attributed to the Golden State Killer first began in 1974, in a California town called Visalia. Over a period of approximately two years, the small town was plagued by a burglar, who authorities said often left more valuable items in the home in favor of less expensive but more personal items like monogrammed cuff links or class rings.

The Visalia Ransacker, as he was called, would also frequently scatter women's clothing — including lingerie — across the home during his thefts, according to authorities.

But in 1976, experts believe the Ransacker moved from Visalia to the Sacramento's eastern area and progressed from theft to sexual assault and rape. Between 1976 to 1979, in areas surrounding Sacramento (like Contra Costa County, Citrus Heights, and Rancho Cordova) numerous women came forward to say they were sexually assaulted by a masked intruder.

Eventually, the East Area Rapist — as he became known in the media and communities — began attacking couples.

Victims said he would spend a lot of time in their homes, scaring them with his presence even hours after an attack. Authorities believed he conducted extensive reconnaissance on the homes of victims and even unlocked doors and windows or pre-planted weapons before an attack.

After 1979, he disappeared from the Sacramento area, but a string of murders in southern California suggested he had moved on to a new community. He's suspected of murdering at least 13 people in southern California from 1979 to 1986, earning him a new moniker: "The Original Night Stalker."

McNamara brought the crimes of the Golden State Killer to light, first with an article for Los Angeles Magazine, and then with her book 'I'll Be Gone in the Dark'

McNamara, a true-crime writer who created the blog True Crime Diary, did extensive research on the East Area Rapist and the Original Night Stalker throughout her career. She believed all the crimes had been committed by the same individual and gave him the name "The Golden State Killer."

In 2013, McNamara published an in-depth and gripping profile of the crimes for Los Angeles Magazine, titled, "In the Footsteps of a Killer." The article, detailing the East Area rapes and the southern California killings, garnered significant attention for both McNamara and the Golden State Killer.

But McNamara's deep dive into the crimes didn't stop there. She continued researching and reporting on the case, eventually garnering a book deal from HarperCollins. McNamara also frequently worked with law enforcement, including now-retired detective Larry Crompton, and now-retired investigator Paul Holes, on the case, offering insights and potential leads.

In 2016, McNamara died suddenly, leaving behind her husband, comedian Patton Oswalt, and their young daughter Alice. Oswalt and some of McNamara's fellow true crime writers, however, recognized how invested she was in the case of the Golden State Killer and worked to publish McNamara's book "I'll Be Gone in the Dark" posthumously, in 2018.

The title of McNamara's book is a reference to something the Golden State Killer said to one of his victims after an attack. He reportedly told them, "You'll be silent forever, and I'll be gone in the dark."

The new HBO documentary series focuses on McNamara's impact on the case, as well as the toll it ultimately took on her

As brilliant and gripping as McNamara's book is, the docuseries does an excellent job of exploring McNamara's fascination with the case, as well as the actual details of the Golden State Killer's crimes. Included in the six-part series are interviews with women who survived attacks by the Golden State Killer, some of whom are just now coming forward to tell their stories.

Oswalt and some of McNamara's former colleagues, including true-crime writer Paul Haynes, also feature prominently, as do detectives like Crompton and investigators like Holes who've also worked tirelessly on the case.

Even though McNamara's work brought the case a great deal of attention, and may have even helped police apprehend a suspect (more on that later), the series doesn't shy away from showing how deeply draining the research and writing was for McNamara. As one might suspect, combing through old police reports and graphic crime scene photos pushed her to the brink of exhaustion.

Ultimately, the series does an excellent job of highlighting just how important the case was to McNamara — and how easy it is to get drawn in by a search for a faceless and nameless killer.

The documentary also includes an important update about the case

Just a few months after McNamara's book was published in 2018, police in Sacramento made a shocking announcement: After decades of dead ends, they'd finally arrested a suspect in connection to the Golden State Killer rapes and murders.

On April 24, 2018, 74-year-old Joseph James DeAngelo was taken into custody after DNA evidence reportedly linked him to some of the crimes, according to investigators.

DeAngelo has remained incarcerated since his arrest in 2018, and recent reports suggest that he'll plead guilty to dozens of criminal charges — including kidnapping and murder — later this month in order to avoid the death penalty.

While the most recent development in DeAngelo's case wasn't included in HBO's documentary, the series does focus on DeAngelo's life and potential connection to the crimes. Several of his family members were also interviewed in the show and expressed their sadness and disbelief at DeAngelo's case.

Critics have reacted positively to 'I'll Be Gone in the Dark' and its portrayal of McNamara

Mike Hale of the New York Times praised director Liz Garbus' integration of McNamara's voice into the series.

"She not only makes McNamara a presence, she also makes her the primary storyteller, through a host of ingenious — if not always wholly transparent — strategies," Hale wrote. He highlighted how seamlessly Garbus merged actual recordings of McNamara with present-day interviews and recordings, and called the show, "an impressive feat of direction and editing."

Hank Stuever of the Washington Post was similarly admiring of the series' approach to McNamara's work.

"'I'll Be Gone in the Dark'... is a complex and thoughtful attempt to comprehend mutual fixations — not only as it pertains to the psychopathy of a serial rapist and killer, but also the allure that such a string of crimes can have on the professional detectives and determined amateurs trying to identify him," Stuever wrote in his review.

And Time's Judy Berman also praised the show, calling it "fantastic" and "an unusually empathetic true-crime story that feels complete at last."

'I"ll Be Gone in the Dark' premieres Sunday on HBO

You can watch the trailer below.

• Read more:
• 'I'll Be Gone in the Dark' director Liz Garbus says law enforcement was critical to solving these crimes — even though that's not always the case
• 'I'll Be Gone In The Dark' director believes we're drawn to true crime stories because 'you can close the book, you can turn off the TV, when in real life, you don't have that power'
• Everything we know about Joseph DeAngelo — the former cop who is the prime suspect in the 'Golden State Killer' case