For years, Joseph James DeAngelo showed up regularly to Charlie’s Café in Citrus Heights, California, a suburb of Sacramento. He would shuffle into his favorite booth and bark orders at the waitresses or complain about his order, according to the restaurant’s owner, Charlene Carte.
Carte couldn’t help but notice his negative attitude and nicknamed him “Mr. Happy.”
Last month, she learned that authorities believe he had another name: the Golden State Killer.
“I was in shock,” she tells PEOPLE about the moment she discovered DeAngelo’s suspected dark side as one of the country’s most notorious serial killers. “It’s scary to know I was that close [to him].”
DeAngelo — a 72-year-old former police officer, retired mechanic and father of three — was arrested on April 24 and soon charged with murder in eight of the 12 killings committed by the Golden State Killer in the ’70s and ’80s.
Police say DeAngelo is also suspected of the four other homicides.
Over a 10-year-period, from 1976 to 1986, the Golden State Killer was linked by DNA and method to 12 slayings, 45 sexual assaults and more than 120 burglaries from Sacramento to Southern California’s Orange County.
The killer’s victims ranged in age from 13 to 41 and included women at home alone or with their children or husbands. The attacks began in Sacramento in 1976, with the June 18 rape of a woman in the Rancho Cordova-Carmichael neighborhood.
Authorities have said DeAngelo only came onto their radar recently and was caught through the use of DNA.
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“This guy has been on the run for 40 years,” Carte tells PEOPLE. “This is scary, knowing I’ve talked to this man, had many conversation with him, dealt with his attitude and anger. And any time, he could’ve snapped.”
At least twice a week before his arrest, Carte says DeAngelo would come into the lively restaurant that serves country-style home cooking between 10 a.m. and 1 p.m. and order breakfast or lunch. He often got the tuna salad.
The restaurant’s other regular customers include law enforcement, Carte says, from detectives to SWAT team members.
“He never showed any signs that he was on the run,” she says. “He never showed any signs that he was a killer or a rapist. He was just your Average Joe, but a grumpy old man.”
According to jail records, DeAngelo is being held at the Sacramento County Main Jail without bail. He is 5-feet-11-inches and weighs 205 lbs., records show.
“We have the law to suggest that he is innocent until he’s proven guilty and that’s what I’m going to ask everyone to remember,” his attorney, who previously declined to comment to PEOPLE, said after DeAngelo’s initial court appearance, according to the Associated Press. “I feel like he’s been tried in the press already.”
It is unclear if DeAngelo has pleaded to his charges.
“I feel sorry for all of the women and what he did to them,” Carte says. “He hurt a lot of people. He thought he was going to get away with it.”