Roubal operated across the early 1990s in Czechoslovakia, killing victims he encountered through ordinary transactions — taxi rides, classified ads, car rentals — then taking their vehicles and property almost immediately afterward. The pattern of acquisition was consistent enough that possession of a dead man's car became, more than once, the first sign to the outside world that something was wrong. His convictions, eventually secured after a procedurally troubled trial, covered five murders, though several further disappearances connected to him were never resolved due to the absence of remains.

His killing campaign unfolded across nearly two years and two countries, making him one of the most geographically mobile serial killers of the 1920s — a period when coordinated interstate law enforcement barely existed. He targeted landladies responding to room-for-rent advertisements, a method that gave him access to victims while evading suspicion for months. The breadth of his movements, from the West Coast through the Midwest and into Canada, repeatedly outpaced local investigations until Canadian authorities finally closed the net.