A participant in the "Kolínský Gang" operating in the Czech Republic during the mid-1990s, Biederman served as the group's primary instrument of violence across a series of robberies and contract killings. His victims included a department store security guard, a small business owner murdered for money that ultimately wasn't there, a gas station attendant killed during a robbery, a former accomplice eliminated for property interests, and a man targeted as a debt-collection measure by outside contractors. What distinguishes his case is the range of contexts in which lethal violence was employed — opportunistic, premeditated, and hired — and his apparent willingness to act where others in the gang declined.

Over the course of seven years, Zhang and his associates carried out a sustained campaign of armed robbery across five Chinese provinces, leaving a trail of casualties that made him one of the most wanted criminals in the country during that period. The scale and duration of the operation — spanning dozens of locations and resulting in dozens of deaths and injuries — drew intense public attention and ultimately a nationally publicized manhunt.