PHOENIX -- The lanky, bespectacled man walked into a bank in a strip mall on Tucson's northern edge with a gun, demanded that a teller hand over an undisclosed amount of cash and made his escape on foot.
Experts say the heist on Friday at the Pyramid Federal Credit Union branch represents a rarity in the world of bank robbery: The suspect, who was arrested the next day, is 80 years old.
And as it turns out, suspect Robert Francis Krebs has a decades-old criminal record for stealing from banks, including a 1981 robbery in Florida in which a branch manager and a teller were handcuffed and left in a vault.
Robert Francis Krebs served more than 30 years in prison for the bank robbery near Orlando and has a 1966 conviction in Chicago for embezzling $72,000 from a bank where he worked as a teller. He also did time for theft and armed robbery convictions from Arizona dating back to 1980.
He was released from prison in Florida last summer and has since been found to have violated his probation because he didn't disclose his whereabouts to authorities, according to the Florida Department of Corrections.
Krebs, who is jailed on a $50,000 bond, was booked on suspicion of armed robbery in the Tucson, Arizona, robbery. It's unclear whether Krebs has yet been assigned an attorney.
Tucson police spokesman Officer Chris Hawkins said investigators are trying to determine the motive behind Friday's robbery.
William J. Rehder, a retired FBI bank robbery expert who isn't involved in Krebs' case, said it's unusual for elderly people to carry out robberies. Typically, bank robbers are in their 20s.
Rehder said Krebs' motivations are likely two-fold: He misses the thrill of pulling off a bank job and needs money, given that he's an octogenarian with little potential to earn money after spending decades in prison.
"This guy sounds more like he is hooked on the action," Rehder said.
Krebs isn't the oldest bank robbery suspect.
Rehder pointed out the case of J.L. Hunter "Red" Rountree, who had been dubbed America's oldest bank robber.
Rountree was convicted of committing robberies at banks during the late 1990s and early 2000s in Mississippi, Florida and Texas. He committed two robberies in his mid-80s and was 91 at the time of his last heist. He died in federal prison a few months before his 93rd birthday.
In the Tucson robbery, Krebs was arrested after a hotel employee, who had refused to give him a room because he didn't have a credit card, later recognized him from surveillance photos that were posted on social media. Officers then went to other nearby hotels and eventually located him.
The Tucson Police Department, which arrested Krebs, and the FBI have declined to confirm that Krebs had prior convictions for robberies.
But The Associated Press confirmed Krebs' convictions by matching his birth date to prison records in Florida, information given by prison officials and news clippings from his criminal cases.
In the 1981 robbery in Florida, Krebs stole $8,300 from a bank near Longwood, Florida. The branch manager and teller had tripped a silent alarm and were later put into the bank vault, according to news accounts by The Orlando Sentinel.
Krebs, who was arrested when walked into the bank's parking lot, was disguised in a red wig, had cotton in his cheeks and varnished his fingertips to leave no fingerprints. Investigators discovered three getaway cars parked along his escape route, according to the newspaper.
Prison officials confirmed that Krebs had theft and armed robbery convictions in Arizona, but no records were available that would provide specifics in the cases.
A few months before the Florida robbery, Krebs was considered a suspect in an April 1981 robbery at a bank in Tucson in which four men stole $3.3 million. But the Sentinel noted in a 1988 news story that Krebs was no longer considered to be a suspect.
Months before the Tucson robbery, a man helped Krebs escape from the custody of the Pima County Sheriff's Office after he was arrested for driving a stolen car. Krebs' associate drew a gun and held two sheriff's deputies at bay while Krebs escaped, according to an AP story on the 1981 robbery in Tucson.
News researcher Rhonda Shafner in New York contributed to this report. Follow Jacques Billeaud at www.twitter.com/jacquesbilleaud. His work can be found at https://www.apnews.com/search/jacques%20billeaud.