The first day of an inquest into the death of Gore preschooler Lachlan Jones has wrapped up, with his mother still giving evidence.

The three-year-old was found dead in a council sewage oxidation pond, about 1km from his home, on 29 January 2019.

His mother had reported him missing earlier that evening.

Read more: The Detail: Quest for answers over three-year-old's death

Two police investigations found he accidentally drowned after wandering off and there was no evidence of neglect or criminal liability.

But his father has disputed these findings, obtaining expert reports that suggested insufficient pathological evidence to support drowning as the cause of death and deficiencies in the police investigations.

The coronial inquest will consider whether the pathologist was correct to conclude he died from drowning, the circumstances that led to him being found in the pond - including if neglect was involved, whether the evidence supports his father's allegations, and if anyone else was involved in his death.

Coroner Alexander Ho would also examine whether further steps could be taken to yield more evidence if that currently available was not enough to answer these questions, and any recommendations to reduce the chance of similar deaths.

Lachlan's mother spent most of Monday on the witness stand in the Invercargill District Court.

However, all of what she said is suppressed until she finishes giving her evidence.

Coroner Ho said Lachlan's death was unimaginable and he hoped the inquest would find answers.

The Independent Police Conduct Authority would be carrying out its own review.

Initially, WorkSafe charged the Gore District Council with failing to comply with a duty that exposed people to the risk of death or serious injury.

That was downgraded, with the council pleading guilty to failing to perform a duty and being ordered to pay $55,000 in reparation to each of his parents, along with about $19,000 in legal costs over his death.

The first phase of the coronial inquest is set to run for three weeks.

Reproduced with permission