Mother, grandmother sentenced for baby's death in hot car

The mother and grandmother of a baby who died after being left inside a hot car while they smoked synthetic cannabis have been sentenced to three years in prison.

A judge has indicated the baby's father will receive a sentence of home detention, but that's been adjourned till a later date.

Isaiah Neil was just eight months old when he died at the family home in Ruatoki in the Bay of Plenty in November 2015.

He'd been left in a hot car for several hours until his father Shane Neil found him - but Neil didn't immediately call emergency services.

Earlier in the day Isaiah's mother Lacey Te Whetu and grandmother Donna Parangi drove to Kawerau with him in the backseat to purchase some synthetic cannabis.

The baby fell asleep in the car, and after returning home his mother and grandmother decided to leave Isaiah in the back.

The windows and doors of the vehicle were shut.

High Court Judge Justice Graham Lang says the temperature in the vehicle would have risen rapidly.

"Evidence was that within an hour it would have risen up to around 40 degrees," he said.

Te Whetu and Parangi then consumed the synthetic cannabis they'd bought, and Parangi told her daughter to go inside for a sleep.

The court heard Parangi tried to minimise the effect the drugs had on her, but the Justice Lang says he had no doubt she also fell asleep.

"By sending your daughter to sleep you took responsibility for Isaiah. When you then smoked synthetic cannabis you must have known the effect that would have had. I consider you had significant culpability in Isaiah's death," Justice Lang said.

Isaiah's father Neil was also at the house at the time, and later chose to partake in the drugs too.

He then fell asleep next to Te Whetu, not knowing his son was left in the hot car.

At about 4pm Neil found baby Isaiah and removed him from the vehicle. He described him as hot, sweaty and lifeless.

He couldn't tell if his son was breathing, but instead of calling an ambulance he took him to Te Whetu.

"Your culpability Mr Neil lies with the fact that you discovered him in an unwell state. You now know it was up to you to alert emergency services. You had consumed synthetic cannabis, and your judgement was clouded," Justice Lang said.

Describing herself as "half-stoned", Te Whetu said Isaiah was hot and sweaty, but it didn't occur to her that he may be dead.

Te Whetu then laid him down in his cot believing he was still asleep.

"You should have taken immediate steps when you saw Isaiah in such a distressed state," Justice Lang said.

Baby Isiah then lay in the cot unattended for another three hours before an ambulance was called.

"Any death of a young child is tragic, and even more tragic when it is needless and as a result of repeated failure by the guardians and parents," the judge said at the sentencing.

"There was no need for [Isaiah] to die."

Lawyers for all three defendants said their clients were remorseful.

Parangi's lawyer Susan Gray said her client has been a caring mother and grandmother.

"She will live with the consequences of this for the rest of her life."

Te Whetu's lawyer Bill Lawson told the court Isaiah's death had completely turned her client's world upside down.

The lawyer acting for Neil said his client will forever carry the guilt of his son's death, but told the court he didn't share the same level of responsibility as the other two defendants.

"Even though his steps were inadequate they were not anywhere near the culpability of the other two because he had no idea the child was in the car."

Both Te Whetu and Parangi wiped away tears as the sentence was delivered in front of a full public gallery.

Supporters shouted out "love you" as the pair were taken away.

Neil will be sentenced at a later date.