In 1960, police discovered the body of a man in a central Auckland apartment, but it is the disappearance of his wife, Cynthia Grierson Jackson that has baffled police for more than half a decade.

Neighbours describe one night where there were loud voices coming from the apartment of Cynthia Grierson Jackson and her husband, Michael.

Otherwise, there was nothing to suggest the grisly scene police would discover a couple of days later.

Scott Bainbridge, author of Without a Trace, investigated the disappearance of Cynthia Grierson Jackson and police discovered Michael Grierson Jackson died of blood loss after castrating himself.

His wife has never been found.

The only lead police had is that days before his death, Michael returned Cynthia's uniform to her workplace and told her colleagues she had left him.

Go to this episode on rnz.co.nz for more details