Mr Bennett said his book told the whole story, from the murder to Mr Pora's exoneration.
He said the thing he most wanted to do was show New Zealand, and the world, the Mr Pora he had gotten to know.
Mr Bennett was contacted by private investigator Tim McKinnel to help him get justice for Mr Pora and tell his story.
He said Mr McKinnel always made the strong point our police force did an extraordinary job.
"Most of the time we get it right. When we don't get it right, we get it catastrophically wrong."
A problem with miscarriages of justice was the people who suffered most were very likely Maori and Pacific Islanders, he said.
He said Maori and Pacific Islanders were unequally represented in the justice system and there were also problems with the appeal system.
Mr Bennett has been touring New Zealand promoting the book, with Palmerston North being the next stop. His book was released last month.