Born on September 6, 1956, in Levice, Czechoslovakia, Jozef Roháč—known as Potkan (“Rat”)—came from a troubled family of five siblings. His father, an alcoholic, would occasionally beat the children. Roháč later described his childhood as unhappy and marked by frequent fights, a foundation for his later life of crime.

After completing his compulsory military service, Roháč attempted to flee the communist regime by requesting travel to Austria. His application was denied, and his passport was confiscated. Undeterred, at just 29 years old in 1985, he took something extraordinary: he kidnapped the Deputy Minister of Health, aiming to use the hostage to negotiate his escape. The attempt faltered at the Petržalka–Berg border crossing. The deputy's health deteriorated, prompting Roháč to surrender—reportedly to prevent harm.

After his release in 1990, Roháč slipped quietly into the Slovak underworld, leveraging his reputation and prison connections to rise as an explosives expert. Known for meticulous planning and a near-perfect success rate, he was soon feared across regional criminal networks.
Assassination of Róbert Remiáš (April 29, 1996): Roháč planted a bomb beneath Remiáš’s car, which exploded on Karloveská Street in Bratislava. Witnesses reportedly heard Remiáš scream before succumbing to the blast. The assassination, believed to have political undertones involving the secret service, remained officially unsolved—charges against Roháč and accomplices were dropped in 2006.
Hit on Róbert Holub & Štefan Fabián (1997): Roháč twice tried to kill Holub. The second attempt occurred inside a bar, where he killed Fabián and severely wounded Holub; Holub later died in a hospital shooting that Roháč also carried out.
Assassination of Eduard Dinič (May 9, 1998): Striking with chilling precision, Roháč remotely detonated 5 kg of TNT under a pavement, killing Dinič. The explosion sent body parts hundreds of meters and left a crater in its wake
Killing of Róbert Dinič (October 4, 1998): Roháč ambushed Dinič with a submachine gun upon his arrival at a house. He shot him and his bodyguard and detonated a van, ensuring their deaths—and the collapse of the Dinič criminal group.
Assassination of Tamás Boros (July 2, 1998): Roháč planted a bomb under Boros’s car in Budapest, which killed Boros and three innocent bystanders—marking the first time civilians were killed in Hungarian mafia violence
Attempt on Ivo Ružič (December 2, 2004): The last known attempt. Roháč detonated an explosive near the entrance of a building housing Ružič. The blast collapsed a wall and severely injured Ružič and his bodyguards; several others and dozens of cars were damaged.

Roháč evaded law enforcement for nearly a decade, despite Interpol searches. He was arrested in Hungary in 2008 for an attempted bombing, serving a brief sentence before his release in 2010. In April 2011, he was extradited to Hungary for trial relating to multiple assassinations. In 2016, prosecutors sought life imprisonment; Slovak authorities also convicted him in absentia and imposed a life sentence by the Supreme Court in December 2018.