The Eastern Bay of Plenty area commander said police undertook an "extensive visual search" and the body was not visible to any of the emergency service personnel at the scene.
"Police had been led to believe that there were only two occupants of the car - one who was in custody and one who was receiving medical treatment for minor injuries."
However, 45 minutes later, Daniel Paruru was completing his bus run with three children onboard when he saw what he thought was a glove sticking out of the ditch.
"I didn't believe it was a hand - I had my mind made up that it was a glove. I'd thought, surely they wouldn't have left a hand there," he told the Herald last night.
To put his mind at ease, he stopped after returning from Opotiki to find Mr Porter's submerged body.
"It didn't look real ... there was a dead body in the drain."
He drove to the nearby house of his niece, Cherie Watene, and her grandmother, Gail Williams, who went to look for themselves.
"His hand was sticking out of the water ... it was like a nightmare. After that I said take me home," Ms Watene said. "We came back to ring the cops and 10 minutes later they were back out there."
Mrs Williams stayed with police at the scene throughout the evening.
"It was very strange to find him there, sticking out of the water, to find him on his side," she said.
"I don't know how many of the emergency vehicles attended the actual accident but obviously they had the ambulance here, the police were here and the tow truck ... and when they pull a vehicle away surely they look behind."
Speaking after Mr Porter's funeral yesterday, his mother Clara Porter said she would be lodging a complaint.
"They left my son lying in that water with his hand up. The police didn't do their job, they left him behind," she said.
"It's not good enough ... they never looked properly and my son died in that drain."
Mr Paruru described the incident as "bloody weird" and said he was annoyed.
He blamed the driver for drinking and driving and said Mr Porter's body would not have been left behind if they had told the police.
"But it's no excuse for a body to be left behind, for sure," he said.
"I don't want to be condemning the cops and emergency services because they do a good job but they still failed - they left a body behind."
Ms Venables said a full crash investigation was under way and it was likely charges would be laid.
Mr Porter's death has been referred to the coroner. The crash served as a timely reminder about drink-driving as the festive season approached.
"Unfortunately, despite all the advertising, crashes, deaths and apprehensions, drink-driving is still a major problem in the Eastern Bay of Plenty area."
