Authorities have dubbed the man, "the blue note bandit" after he presented his demand on blue paper during his first robbery last November.
Sunday around 2 p.m., he hit another bank inside a Ralph's supermarket, marking his 14th bank robbery in just two months.
"I don't think there's ever been a bank robber hit that many banks in a short time frame," said Jim Amormino of the Orange County Sheriff's Department.
The suspect has targeted banks in South Orange County, from Dana Point to Irvine.
"The demand notes always say, 'Large bills only. Hurry up,'" Amormino described.
Authorities say he also mentions that he has a gun and threatens others will get hurt if the teller doesn't hurry up.
"He's bold. When you take people on, it's called chutzpah. He doesn't care," said Roselyn Gudes of Monarch Bay.
The suspect believed to be in his 40s has worn Quiksilver pullovers and always wears a hat, often a baseball cap. A couple of times, he's worn a fedora.
Authorities say he has tanned skin, stands about 5 feet 10 inches to 6 feet tall and weighs about 200 pounds.
"He does have a gap in his two front teeth," Amormino said. "It's not that he's good, he's only been lucky but his luck will run out."
A $20,000 reward is being offered for information leading to the arrest and conviction of the blue note bandit.
If you can help investigators, call the OCSD at 1-866-TIP-OCSD.