LETS CLEAR SOMETHING UP 
 I have done extensive research on the double homicide (1981) you mentioned and the earlier murder committed by the same person in 1969 in New Plymouth.  99% of the recollections of the details are always wrong and the case has wrongly become a legend rather than a horrendous double homicide. I have studied the court notes, scene examinations, pathologists reports, witness statements and even the statements by the accused and believe me, its not easy to digest. 
 A couple of things I can clear up though: the “house across the road from the pub” is not the location. The legend/rumour about “excised genitalia” is just that – legend. 
 These murders were, however, horrific and not really something that needs to be described on the internet.