Damian Lau
Early in the story, Leung Pak-yeen (Damian Lau) was in a dispute with his wife (Mary Hon) and they argued on a building rooftop. The wife fell from the building top and the murder was witnessed by one of the construction workers. The worker turned out to be an illegal immigrant in Hong Kong. He spent a great deal of time escaping Leung Pak-yeen and just about anyone who questioned his identity.