The man, who made no effort to disguise himself, robbed the Bank Atlantic branch Saturday and in February and June, Broward County Sheriff spokeswoman Dani Moschella said.
"He handed one teller a bag, and said, 'Do this now.' To the next, he said, 'You're to open your drawer and give me everything. I don't want to hurt anybody,'" Moschella told CNN Tuesday.
The man apparently was not worried about being recognized, Moschella said, adding the suspect did not show a weapon during the robberies.
Saturday, the suspect wore black pants, a black T-shirt, black gloves with a red stripe and a black hat with red and yellow stripes, witnesses said.
He walked out with an undisclosed amount of money in a white plastic grocery bag before breaking into a run across the parking lot, Moschella said.