Today was the final day of the first phase of Coroner Alexander Ho’s inquest into the 2019 death of the 3-year-old from Gore.
Police admitted they "missed steps" in the initial investigation and today Detective Inspector Stu Harvey was questioned at the inquest in Invercargill about the second investigation, which he led.
The witness explained that the first investigation relied heavily on eye witnesses, none of whom could identify the child they saw as Lachie.
He said on the night, everything had to be done quickly as time was "of the essence".
"You’ve got to look at the combination of all those witness statements," he said.
He said the description of the distinctive clothing Lachie wore was helpful.
Det Insp Harvey explained the investigation was still open.
"Are you now aware of any further evidence?" counsel assisting the coroner Simon Mount, KC, asked.
"We're still doing inquiries in regards to information coming in," the witness replied.
Lachie was measured a metre tall at his last doctor’s visit.
Sergeant Hua Tamariki was involved in the initial investigation and said it would be "almost impossible" for someone to climb out of the pond due to the slope near the edge and the surface of the ground.
But Det Insp Harvey’s investigations showed the rough concrete around the edge of the pond and under the water "felt secure under foot".
"The base felt firm and stony with only minimal movement of the clay when prodded."
The court heard that bodies tend to sink in fresh water but there were lots of variables that could impact the buoyancy of the water.
Det Insp Harvey said he did not make inquiries into chemicals in the pond, or any other variables that could have caused Lachie’s body to float.
Coroner Ho directed that information about the composition of the water and the slipperiness of the surface be provided by the Gore District Council.
He also asked that information about currents in the pond and wind on the night be provided - something Det Insp Harvey did not thoroughly investigate.
"There wasn't any evidence to suggest the body had been moved any distance," Det Harvey said.
The witness said he had reflected on what could be learned from the first investigation and accepted there was some oversight and a forensic post-mortem should have been carried out.
"If the post mortem had been done properly... I think that would’ve given some certainty to Mr Jones and Ms Officer as to how Lachlan died," he said.
Det Insp Harvey’s evidence marked the end of the first phase of the inquest.
The court heard expert witnesses in the second phase in August would include three forensic pathologists, an expert investigator to be called by Lachie’s father Paul Jones, and a child behaviour expert.
"I haven’t lost sight of the fact that it's been over five years since Lachie died," Coroner Ho said.
"We continue to work, I believe, for Lachie."
