Mr Roberts said the boy's family was devastated.
A family member in Kawakawa said yesterday they did not want to comment.
Tareha's cousin Wiremu Mahanga earlier said the boy loved horses and was not afraid to break in wild ones.
"In the summer, when the grass was high, you'd see these little heads pop up and he was one of those kids. The horses would be running around them," he said.
He said Tareha's grandmother had been his caregiver when the parents were away for work.
"His grandmother stays just down the road. I saw some lights outside my front gate and it was the ambulance.
"The horse had dragged my little cousin through about two fences and stopped at my driveway," Mr Mahanga told the Herald on Sunday.