The suspect, 65-year-old Nicholas Raymond Gonzales, reportedly robbed the Citibank at 2860 Cochran St. on Sept. 1.
Authorities say the robber told the bank teller he was armed with an explosive device before receiving an undisclosed amount of money and fleeing the scene.
The same Citibank was robbed July 9 by a suspect who carried out the same threats.
During the investigation, the Simi Valley Police Department posted the suspect's image, captured by the bank's surveillance camera from the second robbery, on their Facebook page. Within hours, a private citizen recognized the suspect and called police.
Gonzales was located in Los Angeles and arrested on Monday. Police believe he is responsible for both robberies.