In recent years police methods of investigation have undergone great changes to meet the needs of the modern world. With the expansion of scientific detection, tremendous advances have been made in every department of law enforcement, with a corresponding emphasis on police recruitment, training, and experience. But like every other country in the world, and despite the high standards of efficiency set by its Police Force, New Zealand has its list of crimes which have defied every effort to solve them. In their day these cases aroused great interest, in large measure because the mysteries were never unravelled to the full satisfaction of the law. Many are still referred to from time to time – a few of the more notable unsolved crimes are dealt with here.