BARDSTOWN, Ky. -- A bank robbery by a 78-year-old may sound bizarre, but Bardstown police believe an elderly man put much thought into it.

Now, police are trying to figure out what drove William Rucker to rob a bank in Bardstown, reported WLKY-TV in Louisville, Ky.

"He really hasn't said why he did it. I don't know whether it was money problems. He's not saying," said Bardstown Police Chief Charles Marksbury.

Rucker was indicted last week on charges of robbery and is being held in the Nelson County Jail on a $100,000 bond.

According to police, Rucker went to the drive-through window with at a Town and County Bank and gave the teller two Wal-Mart bags.

"One the teller took, basically he said he had a bomb in one of the bags and to fill up the other bag with money," said Marksbury.

There was no bomb, only round pieces of wood with black tape wrapped around them.

Marksbury said Rucker drove away from the bank in a vehicle that had stickers on it like you would find in a car lot. Officers checked dealerships in the Bardstown area, including one six blocks from the bank.

"Turns out this guy comes in earlier that morning and wanted to test-drive it, robbed the bank, took the car back and parked it," explained Marksbury.

The dealership had made a photocopy of Rucker's driver's license, so it didn't take long for officers to track him down at his Bardstown home. They said they found the cash, minus $100, in the home.

"You know, you don't run across too many 78-year-old bank robbers, especially through the drive-through," said Marksbury.

Rucker, who will turn 79 next month, declined to speak with WLKY.

His wife said she too is trying to figure out why her husband robbed a bank.