Authorities Tuesday circulated security images of the so-called Cold Hands Bandit and an accomplice, who have robbed at least 15 banks in Los Angeles County.
"The (bandit) received this moniker because of his proclivity to keep his hands concealed while committing the holdups," Sheriff's Deputy Lillian Peck said.
Detectives began their investigation in November, following the robbery of a bank in the 8400 block of East Valley Boulevard in Rosemead.
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"They soon discovered this was just the first known heist by the pair of brazen bank robbers," Peck said. "Detectives identified the Cold Hands Bandit's pattern of passing a demand note and threatening violence if his demands for money are not met."
Both suspects are described as black and 25 to 30 years old.
The Cold Hands Bandit was further described as 5 feet 6 inches to 5 feet 8 inches tall, with a thin build, and his accomplice is 5 feet 9 inches to 6 feet tall and weighs 190-200 pounds.
In at least one crime, the suspects fled in a late model, silver Dodge Charger.
Anyone with information on the case was urged to call the sheriff's Major Crimes Bureau at 562-946-7893; the LAPD's Robbery-Homicide Division at 877-527-3247; or the FBI at 310-477-6565.