Paul Jones, the father of Lachie Jones, said looking into the investigation was not going to fix anything or answer how his son got out there.
"It’s not an investigation, it’s just another way for them to try and prove what they’ve done is right," he said.
Police admitted in a media release yesterday they "missed some steps" early into investigating Lachie’s death after he was found floating face up in an oxidation pond on January 29, 2019.
In the past, Mr Jones was critical of how police handled their investigation into his son’s death and disagreed with the police ruling the death as a drowning.
Southern police district commander Paul Basham has requested national investigations overview of the handling of the original investigation.
"In ordering the review, Superintendent Basham is working to provide reassurance that police have done everything possible to find answers about Lachie’s death,"a police spokesman said.
"Police are well aware of continued reporting and concerns raised by some parties about our investigation and re-investigation of the case.
"To address that concern, we have asked one of police’s three national investigation leads, Detective Superintendent Darryl Sweeney, to lead this review, to provide a senior and objective analysis of the police investigations.
"His work will include reviewing the police file, police decisions and actions in the early stages of the original investigation and the subsequent re-investigation by a detective inspector."
Police said it was appropriate to acknowledge their re-investigation identified some steps missed in the original investigation.
To Mr Jones, the investigation was "neither here nor there".
"Looking to them is not going to fix anything or answer how my son got out there," he said.
He saw nothing positive in the decision yesterday.
Police initially concluded Lachie had wandered off and his death was an accident.
However, his father, unable to believe his son could have wandered off barefoot 1.2km away from home, was fighting to this day to find more answers.
Mr Jones hired Karen Smith, a retired United States crime scene investigator, who spent more than 400 hours investigating his son’s death.
Ms Smith said the New Zealand police investigation was an "across-the-board system failure".
"She is a world-renowned and world-class investigator, and she had all these questions," Mr Jones said.
"Yet all these people from the New Zealand Police who investigated, not one of them came up with any of those questions."
Mr Jones said there were too many unanswered questions.
"Why doesn’t the police try answering the questions instead of flipping them under the carpet?
"They won’t even ring me. No police or anyone ever rings me, because they have no answers.
"This investigation doesn’t sit well with me."
