Between 1989 and 1990, Leibowitz robbed 21 bank branches, mostly in the Tel Aviv area, stealing around $400,000. His first robbery was at the First International Bank branch in Herzliya Pituah on February 21, 1989. With his identity still unknown, he quickly became Israel's most adulated outlaw. According to Haaretz, he became a folk hero "portrayed as part Robin Hood, part sex symbol." It was widely reported that he used a motorcycle to enter and escape banks, and then hid the motorcycle in a truck readied for that purpose in advance. However, Leibowitz claimed that he never actually used a motorcycle, and that it was a media invention. Rather, he committed the robberies while wearing a crash helmet and a windbreaker to disguise himself. After each robbery, he casually walked outside and placed the helmet with the windbreaker stuffed into it in a nearby alleyway, then headed back to the bank and slipped into the crowd of curious onlookers who had in the meantime gathered outside the bank before being ordered away by the police. Leibowitz calculated that the police would not expect to find the perpetrator still at the scene of the crime. He would wait until the police removed roadblocks set up in the vicinity, retrieve his helmet and windbreaker, and go home with the money tucked in his shirt. Although he would threaten the teller with a pistol, he never harmed anyone during his robberies, and would only fire a single shot into the air.
Police launched stakeouts and set up roadblocks in an effort to catch him. Dozens of bikes were questioned, leading many bikers to adorn their motorcycles and helmets with stickers proclaiming "I'm not the robber." At least four suspects were detained on suspicion of being the Ofnobank, among them a reserve Israeli Air Force officer, and Leibowitz twice committed robberies while suspects were being held. The Ofnobank was speculated to potentially be a former commando or former policeman.
On October 7, 1990, Leibowitz committed his last robbery at the Bank Hapoalim branch in Ramat Gan. That same month, he was arrested near his parents' home outside a bank, which he claims he wasn't even planning to rob.