The inmate found dead in his Mt Eden prison cell had admitted violence and sex charges against women and children spanning a period of four decades.
The prisoner was Liberty Charles Baker, 63, who was due to be sentenced in the High Court at Whangarei on Wednesday after pleading guilty to nearly 80 charges including rape, sexual violation, assault, kidnapping, threatening to kill and grievous bodily harm.
His sentencing was delayed until December but now detectives from Auckland City are investigating the "sudden death" of the remand prisoner after being notified by phone at 8.41am yesterday.
A post-mortem examination is scheduled for today and the death was referred to the Coroner, as well as subject to a review by the Corrections Inspector.
Key questions will focus on the circumstances leading to his death including whether he was threatened by other inmates and if there was sufficient supervision of Baker by prison staff.