Ms Jack said the family had so many questions.
"I think they should have dropped him off at someone's house or put him in the cells for the night. He might have been here today if that had happened."
Issy's funeral was due to be held today at 11am at Te Takinga Marae, Mourea. He will be buried at Motutawa Urupa in Mourea.
"The saddest thing is even when we get to say goodbye it's not going to be over," Ms Jack said.
"We'll still have an investigation and any court hearings."
Rotorua road policing manager Brendon Keenan said a police unit on the way to a violent domestic incident saw what they believed to be a person lying on the footpath in the early hours of Sunday and radioed for an officer in a second vehicle heading to the same incident to investigate.
"On arrival a man sitting on the footpath stood up and spoke with the police officer," Mr Keenan said.
"He indicated he was fine and didn't have far to go. As the officer continued to the nearby domestic incident, he observed the man walking along Te Ngae Rd. He observed him again a short time later walking past the scene of the domestic incident."
He said when the officer heard about the fatal road incident he immediately advised his supervisor that he had spoken with a man on that same stretch of road.
"Police have been able to confirm that it was Israel Jack the officer had spoken with earlier and Mr Jack's family have been advised. This forms part of ongoing inquiries into the death of Mr Jack."