The expert phase of Coroner Alexander Ho’s inquest into the 3-year-old’s death continued in Invercargill yesterday.
In 2019, Lachie was found 1.2km from his Gore home, face up in an oxidation pond.
Police quickly concluded the boy had drowned, but later confessed they "missed some steps" in the investigation.
Lachie’s father, Paul Jones, never believed his son drowned and suspected foul play.
Yesterday, retired major crimes detective Karen Smith, who worked for police in Florida for more than 13 years, said she had a "gift" for identifying overlooked details in cases.
She heard of the Lachie Jones case from her good friend Kelvin Cruickshank — a psychic medium known for his regular appearances on the television show Sensing Murder.
Her opinion was that Lachie was placed into the oxidation pond after his death and an accidental drowning was staged.
Ms Smith said the death should have been treated like a homicide until proven otherwise.
"The reason that we’re all here is that nobody can say for certain how Lachlan got to the oxidation pond," Ms Smith said.
Her evidence paid attention to the actions of Lachie’s mother, Michelle Officer, on the night of his death, gaps in her unverified timeline and possible neglect.
The up to five-hour period after Lachie was picked up from kindergarten was unclear and unverified, she said.
The witness said Ms Officer’s package scanner at the courier depot was used at 5.47pm, but she testified she left work at 5.30pm.
Ms Smith said she did not believe Lachie could have run out of his mother’s sight during the "30 seconds" she
spent speaking with Deborah Thurston, and it could not be proved Lachie was ever at Ms Thurston’s house that night.
Counsel for police Robin Bates said Ms Smith had not considered all relevant evidence in reaching her conclusion.
"Based on your expertise ... you decided that somebody had to be involved in [Lachie’s] death and that in order to achieve that you had to look at, in particular, Michelle’s actions."
"What I suggest you did is what you have accused the police of doing ... coming up with a proposition and ignoring the rest of the evidence, or some critical evidence."
Ms Smith also said Ms Officer displayed signs of being neglectful.
She questioned Lachie’s chronic nappy rash, fungal infection and why he was left with a dirty nappy for an extended period.
The witness thought it was strange that when Ms Officer called police, she was not concerned Lachie might have been kidnapped and went home instead of continuing to search for him.
"The inference being that she’s a bad mother and she might want to get rid of him?" Mr Bates asked.
Ms Smith said she was not accusing anyone of anything, only raising unanswered questions that needed to be looked into.
Mr Bates said there were up to six sightings of a small child in a hi-vis vest running along the street on the night of Lachie’s disappearance.
"There is no evidence of any other children running around in this area on any night ... let alone with a hi-vis jacket on," he said.
"Could we not draw a reasonable inference ... that it might be Lachie?"
Ms Smith said she would need a stronger witness identification to draw that conclusion.
Mr Bates said that from the outset she did not consider it possible Lachie’s death was an accidental drowning.
"As a result of your approach, your hypothesis, for bias or whatever other reason, you have ... given little or no weight to those identifications because they don’t fit in with your theory that somebody put Lachlan in the water," he said.
Ms Smith said while she had not gone into particular detail about the sightings, it was unfair to point out omissions in her brief of evidence, given the oversights by police in the investigation.
She accepted the police theory might be correct, but thought it was unlikely, she said.
The inquest will resume on Monday afternoon.
