Karaoke. Chemistry. Killing. This is the story of a brazen chemical attack at daytime in a busy airport. It claimed the life of the North Korean leader’s eldest brother within two hours. The men who planned and executed the attack escaped, leaving two young women to face the consequences. The man suspected of cooking up the chemical concoction that killed Kim Jong Nam got away after two weeks under arrest. Despite the evidence, Al Jazeera finds he is free and happy. Meet the Karaoke Chemist believed to be behind the most high-profile assassinations of recent times.