An 81-year-old California newlywed mysteriously vanished after marrying his childhood sweetheart — and investigators are wondering whether they have a case of cold feet on their hands.

Robert "Bob" Harrod, who his daughter and some family members say has mild dementia, disappeared from his home in Orange County on Monday — a month after his marriage to Fontelle Heeter, whom he first proposed to 59 years ago.

Police have stepped up their investigation into his whereabouts. They don't suspect foul play, but they haven't ruled anything out, Placentia Police Sgt. Scott Millsap told FOXNews.com.

"We're looking at it with an open mind," Millsap said. "We're chasing every lead, looking under every rock for him."

Harrod's wallet and keys are missing, but his car and glasses were left behind at his house in Placentia, according to The Los Angeles Times.

Millsap said there's a dispute in the family as to whether or not Harrod even suffers from dementia, so police don't think that's the reason for his disappearance.

"I don't think it's dementia," he told FOXNews.com. "Most of the family says he's sharp as a tack." He said investigators don't have a working theory about what happened.

Heeter hasn't heard from her new husband since Sunday. After their June 29 wedding, she went back to Missouri to pack up her things and came back to California Wednesday to move in with Harrod.

Placentia Police Det. Corinne Loomis said detectives initially thought Harrod took off because he had argued with another family member. But they also are investigating whether he left because of post-wedding jitters.

"Maybe he's off cooling off some place, but to think he would blow her off like that doesn't make sense," she told the Times. "There are things in his home that indicate he was planning on welcoming her into his home."

Authorities are studying the missing man's phone and bank records and have searched the neighborhood.

Harrod popped the question to Heeter in 1950, but they broke up when he went to serve with the Marines in the Korean War.

The pair went on to marry other people. Both had children and then were widowed.

But recently fate — or, rather, Heeter's daughter — intervened, after hearing tales of her mother's first love.

She dug up Harrod's phone number and a reunion was arranged. The sparks were still there.

"His wife is very worried," Loomis said.

Harrod is 5 feet 11 inches tall and weighs 140 pounds. He is balding with gray hair and brown eyes and was last seen wearing white pants and a white hat.

Anyone with information on his whereabouts is asked to call Placentia Police at (714) 993-8194 or (714) 993-8168.

Click here for more on this story from MyFOXLA.com.

Click here for more on this story from the Los Angeles Times.

The Associated Press contributed to this report.