He used what little time he had to great psychological effect.
First he placed a reward poster, offering £200 and a pardon for a confession, where the men could see it. And then he moved one to a separate cell so the other three were left to stew in their private suspicions.
The ploy worked. Joseph Sullivan, thinking he might be betrayed, got in first and told Shallcrass what had happened and where the bodies were buried.
He also told him about a murder near Greymouth and alleged that, from the conversations of the other three, they had committed about 30 killings in their New Zealand crime spree.
These crimes were never confirmed but the gang were convicted of the Maungatapu murders. Three were hanged but Sullivan's life was spared.
Shallcrass was promoted to inspector for his great detective work. Even Dick Burgess, the leader of the gang, was impressed.
As he walked to his execution he made a point of shaking Shallcrass by the hand, blessing him, congratulating him on his promotion and complimenting him on his efficient work.
We agree, and Inspector Robert Shallcrass is our New Zealander of the Year for 1866.
From the Herald archives:
'The Maungatapu Murders', New Zealand Herald, 10 July 1866
Further reading:
Animated digital flipbook, NZ History Online
