PICTURED: Bloodied mugshot of former cop, 72, arrested and named by police as the Golden State Killer who murdered 12 and raped 51 over a decade-long reign of terror from the 1970s after DNA links him to four of the killings 40 YEARS on

• The Sacramento County Sheriff's Department arrested Joseph James DeAngelo Jr, 72, late Tuesday night
• DeAngelo is believed to be the Golden State Killer, a serial rapist and murderer suspected of 12 homicides and nearly 50 rapes in Sacramento County in the 1970s and 80s
• DeAngelo is being held at the Sacramento County Main jail on two murder charges and is ineligible for bail
• The arrest comes months after the release of journalist and author Michelle McNamara's posthumous crime book about the Golden State Killer titled I'll Be Gone In The Dark
• The book, released in February, was co-authored by McNamara's husband, actor Patton Oswalt, and fellow journalist Billy Jensen after McNamara's death in 2016
•  DeAngelo is believed to have been fired from the Auburn Police Department in 1979 for shoplifting a hammer
•  The Golden State Killer is suspected of terrorizing southern California between 1976 and 1986
• It's believed his first murder victims were Brian Maggiore and his wife Katie who were chased down and killed while walking their dog in their Rancho Cordova neighborhood on February 2, 1978
• The FBI believe his last crime was committed in May 1986, with the murder of an 18-year-old girl in Irvine
• Jane Carson-Sandler, who survived an October 1976 rape attack and was the Golden State Killer's fifth victim, said she was 'overwhelmed with joy' over his possible arrest 

A former cop has been identified as the notorious Golden State Killer after a breakthrough in DNA testing linked him to some of the 12 murders and 51 rapes the serial killer carried out throughout the 1970s and 80s.

Joseph James DeAngelo Jr, 72, was taken into custody by the Sacramento County Sheriff's Department on Tuesday night on two murder charges for the 1978 deaths of Brian Maggiore and his wife Katie, who are believed to be the Golden State Killer's first murder victims.

He was later also charged with the murders of Lyman and Charlene Smith who were found dead in their home by their 12-year-old son in 1980. 

Despite an outpouring of thousands of tips over the years, DeAngelo's name had not been on the radar of law enforcement before last week. 

Police say a DNA match in the past six days linked him to both crime scenes, but authorities refused to reveal what led to DeAngelo. 

Sacramento Sheriff Scott Jones said detectives with 'dogged determination' were able to get a sample of DNA from something DeAngelo had discarded, though he wouldn't say what the item was. The genetic material was not a match, but there were enough similarities for investigators to return for more and they said they were able to get a conclusive match. 

After watching DeAngelo for several days, deputies took him by surprise Tuesday when he left his home. 

Police are now working to link the 72-year-old unequivocally to the rest of the crimes that profilers have attributed to the Golden State Killer through his modus operandi. It is unclear how many of the crime scenes produced DNA evidence.

DeAngelo was arrested on suspicion of committing four killings in Sacramento and Ventura counties. In a mugshot released by police Wednesday afternoon, DeAngelo's face and head appeared to be bloodied. 

Investigators said DeAngelo has three adult daughters. An old wedding announcement says he married Sharon Marie Huddle in 1973, according to the Sacramento Bee. They are now divorced.

DeAngelo previously worked as a police officer in Auburn, California before he was fired in 1979 for shoplifting a hammer and dog repellent from a Sacramento drug store. He was also a police officer in Exeter, California from about 1973 to 1976. 

Investigators believe he was committing the crimes while he was an officer. 

Before he retired last year, DeAngelo had been working at a distribution center for Save Mart grocery stores. He worked the for 27 years. 

DeAngelo is currently being held at the Sacramento County Main jail and is ineligible for bail, according to jail records.

'We knew we were looking for a needle in a haystack, but we also knew that needle was there,' Sacramento County District Attorney Anne Marie Schubert said. 'We found the needle in the haystack and it was right here in Sacramento. The answer was always going to be in the DNA.'

Orange County DA Tony Rackauckas said they were going to make sure DeAngelo never gets out of jail. 

'This defendant has been able to live here in a nice suburb in Sacramento,' he said during Wednesday's press conference. 

Bruce Harrington, whose brother Keith Harrington and sister-in-law Patrice Harrington were allegedly killed by the Golden State Killer in 1980, appeared at the news briefing to offer a few words to victims. 

'For the 51 ladies who were brutally raped: Sleep better tonight,' he said. 'He isn't coming through the window. He is now in jail and he is history.'

An old newspaper article states that DeAngelo was a police officer in Auburn, and was eventually fired in 1979 for shoplifting from a Sacramento drug store. Auburn City Manager Jack Sausser said at the time that DeAngelo failed to answer any of the city's investigations and there 'was justifiable grounds to remove him from the public sector'. 

Another old newspaper article said DeAngelo was in the Navy and served aboard the USS Canberra, a Baltimore-class cruiser. He left the navy in 1967.  

Interest in the Golden State Killer, also known as the East Area Rapist, was reawakened recently following the release of journalist and author Michelle McNamara's posthumous crime book I'll Be Gone In The Dark.   

McNamara spent much of her career researching and writing about the California rapist and killer, but died before the book was published.

Her husband, actor Patton Oswalt, and friend and fellow journalist Billy Jensen finished the book for McNamara and released it in February. The book quickly climbed to the number one spot on the New York Times Best Sellers list.

Oswalt was among the first people tweeting about the possible arrest of the Golden State Killer as he praised his late wife who spent much of her career researching the murderer.

'I hope you got him, Michelle. I hope THEY got him,' Oswalt tweeted soon after the arrest. 

'If they've really caught the #GoldenStateKiller I hope I get to visit him,' he posted in another tweet. 'Not to gloat or gawk - to ask him the questions that (McNamara) wanted answered in her 'Letter To An Old Man' at the end of #IllBeGoneInTheDark.'

Co-author Billy Jensen has also posted numerous tweets about the possible arrest of the serial killer.

'If you've been following the Golden State Killer case, stay tuned. We will be having a rather large announcement,' he teased, adding: 'Two hours of sleep but an airport chocolate banana smoothie is going to get me through what I hope will be an amazing day. #IllBeGoneInTheDark #GoldenStateKiller #intothelight.' 

According to the FBI, the Golden State Killer terrorized southern California between 1976 and 1986. His crimes began in the summer of 1976 with burglaries and rapes in Rancho Cordova and Carmichael. 

Investigators said he gained access to the homes by prying open a window or door while the victims slept. He would then shine a light in the face of his victims and tie up the female victim. If a male victim was present, the Golden State Killer would tie him up as well before ransacking the home and raping the female victim. 

Detectives said the killer often took small items during his burglaries such as coins, cash, ID cards and jewelry. Some victims told authorities that the killer called them after the crimes. 

It's believed the first victims were killed in 1978. Brian Maggiore and his wife, Katie, were walking their dog in their Rancho Cordova neighborhood on February 2, 1978 when they were chased down and murdered by the Golden State Killer. 

After this crime, he committed rapes and murders in Stockton, Davis, Modesto and the East Bay. The FBI believe his last crime was committed in May 1986, with the murder of an 18-year-old girl in Irvine.

The Golden State Killer's fifth victim, Jane Carson-Sandler, survived an October 1976 attack. Carson-Sandler said her husband had just left for work when the masked man broke into her Citrus Heights home, bound and gagged her and her three-year-old son and then raped her. 

Carson-Sandler, who wrote a book about surviving the attack, said on Wednesday that she received an email from two detectives informing her of the killer's arrest.

'I have just been overjoyed, ecstatic. It's an emotional roller-coaster right now,' Carson-Sandler, who now lives near Hilton Head, South Carolina, told The Associated Press. 'I feel like I'm in the middle of a dream and I'm going to wake up and it's not going to be true. It's just so nice to have closure and to know he's in jail.' 

Debbi Domingo was 15 years old when her mother, 35-year-old Cheri Domingo was brutally murdered by the Golden State Killer. Domingo said she had gotten into a spat with her mother and left the home to stay with a friend, a decision that may have ultimately saved her life. 

Also killed that horrible July 27, 1981 night was Cheri's 27-year-old boyfriend, Gregory Sanchez. 

In a tweet Wednesday afternoon, Domingo said she had not yet commented on the killer's arrest because she was 'digesting'.

'Everyone is wondering why I'm not shouting from the rooftops yet. Digesting,' she tweeted, adding the hashtag: 'UNMASKEDatLAST'.

Neighbors in DeAngelo's quiet Citrus Heights Sacramento suburb said they were stunned over his arrest. Others said he is known to be angry and shout obscenities while he was outside doing yard work. One neighbor told the Sacramento Bee that DeAngelo had 'anger pouring out of him'. 

'It's terrifying to think this man could have hopped the fence and come into my backyard. I have children,' said another neighbor named Beth Walsh, who lives behind DeAngelo on an adjacent street. 'I'm glad to know they caught this guy.' 

Another neighbor, Cory Harvey, told the outlet that 'Joe' - as she calls him - lived in the home with his daughter and granddaughter and is divorced.

DeAngelo had told her that he retired and planned to do a lot of fishing.

Harvey described him as a good neighbor saying he helped pay for a fence her husband put up to separate their yards. She said he was a regular guy, 'except for that quirkiness of getting mad'.

Natalia Bedes-Correnti, who lives a few houses down, said people in the neighborhood used to call DeAngelo 'freak'. 

'He used to have these temper tantrums, not at anybody, just (expressing) his self frustration...usually because he couldn't find his keys,' she told the Sacramento Bee. 

Another neighbor, Eddie Verdon, said he caught DeAngelo prowling on his property. 

'I had the creeps about this guy for a long time,' he said. 

Grant Gorman, who grew up in the house behind DeAngelo, told the outlet that he was so scared of DeAngelo that he avoided playing with his daughter when they were younger. 

'I felt sorry for her,' he said about the daughter, adding: 'This guy just had this anger that was just pouring out of him. He'd just be yelling at nothing in the backyard, pacing in circles.'

 Family members also said they were shocked to learn about DeAngelo's past and arrest. 

James Huddle told Oxygen on Wednesday that DeAngelo allegedly asked him once about the crime spree sweeping across southern California in the late '70s and '80s.  

'He actually asked me about it once,' Huddle said. 'He said: 'What do you think of that East Area Rapist? What would you do, Jim?'' 

Huddle said his sister was married to DeAngelo.