SACRAMENTO, Calif. (Reuters) - An elderly former policeman has been arrested and charged with eight murders attributed to the Golden State Killer, a serial criminal responsible for dozens of rapes and slayings that terrorized parts of California during the 1970s and 1980s, authorities said on Wednesday.

The suspect was identified at a Sacramento news conference as Joseph James DeAngelo, 72, in a case officials said was finally solved by DNA evidence about two months after gaining renewed attention in the bestselling book, “I’ll Be Gone in the Dark.”

Sacramento County Sheriff Scott Jones credited the book with helping to generate new tips but said no information was “extracted from that book that directly led to the apprehension.”

The Federal Bureau of Investigation has previously said that the man sought in the 40-year-old case was tied to 12 slayings, 45 rapes and more than 120 burglaries in and around Sacramento, the eastern San Francisco Bay area and Southern California.

The crime spree spanned 10 California counties in all, said Sacramento County District Attorney Anne Marie Schubert, who recalled she was 12 in 1976 when a wave of violent home invasions shattered a “time of innocence” in which area residents routinely left their doors unlocked.

The suspect, also dubbed by investigators as the “East Area Rapist” and the “Original Night Stalker,” is considered one of the state’s most prolific serial killers, the FBI said.

“Finally, after all these years, the haunting question of who committed these terrible crimes has been put to rest,” Orange County District Attorney Tony Rackauckas told reporters.

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DeAngelo was living in the Sacramento suburb of Citrus Heights when arrested on Tuesday. He had been under surveillance for a few days and was taken into custody without incident as he emerged from his house, Jones said, adding that the suspect appeared “surprised” when confronted.

He is due to be arraigned in Sacramento, the state capital, on Friday.

Jones said DeAngelo was an officer in two small-town California police departments during the 1970s - Exeter and Auburn. DeAngelo was fired from the Auburn force in 1979, Jones said, after being accused of shoplifting a hammer and dog repellant from a store.

Authorities had long speculated the killer had some military or law enforcement training because of his proficiency with firearms and ability to elude capture for so long.

Jones acknowledged that some of the earlier crimes were committed while DeAngelo was a policeman. But authorities said his name had never surfaced as a suspect prior to the latest break in the case, which they said came from a “discarded DNA sample” obtained by investigators.

Efforts to capture the killer were renewed in June 2016, when the FBI offered a $50,000 reward for the suspect, who was known for creeping into the homes of couples at night, tying them up and raping the woman before killing both victims.

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Between 1976 and 1978, he committed a wave of burglaries, rapes and killings in the Sacramento area, then centered his attacks in the East Bay before moving on to Ventura and Orange counties to the south, according to the FBI.

He was formally charged in Sacramento County this week with two counts of murder for the February 1978 killings of Brian Maggiore and his wife, Katie, who were on an evening walk with their dog when they were chased down and slain in what became the first homicide linked to an earlier series of East Bay rapes. Two additional murder charges were filed in Ventura County and four more were brought in Orange County.

The killings were intensively explored in “I’ll Be Gone in the Dark,” published in February. Author Michelle McNamara died in 2016, and the book, which topped the New York Times bestsellers list, was finished by a writer hired by her husband, comedian-actor Patton Oswalt.

Oswalt, best known to television audiences from the hit CBS sitcom “King of Queens,” said in a video posted on social media on Wednesday, “I think you got him, Michelle.”