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, non-expert witnesses gave evidence about text messages that recently came to light.
Mr Tremaine replied saying he did recall telling her that but did not want to tell police about it.
Yesterday, Mr Scott gave evidence that he never said he threw Lachie in the pond and would never do such a thing.
He said he was sick of being "rubbished" by the media and people in his community.
"I think it’s disgusting because I love my little brother," he said.
The woman who told police about the messages gave evidence that Mr Tremaine told her: "Johnny was the one that threw his wee brother into the pond".
"He said he grabbed him, picked him up and biffed him in," she explained.
She said what Mr Tremaine told her made her believe he was saying Mr Scott had killed Lachie.
"The way Tyler said it was a bit too casual for my liking," she said.
The witness said she was "mind blown" when she heard this and did not know what to do.
"All I had was verbal proof and I know that ... you need physical proof," she said.
"Slowly listening to everything over the media, it added up."
The witness said Mr Scott would "terrorise her" as a child.
He said the woman claiming that he "terrorised" her as a child was an attempt to make him look bad and was not true.
"I was always a nice kid," he said.
The woman did not think Mr Tremaine was joking or lying when he made the allegation.
"You don’t joke about that ... that’s sick," she said.
She struggled to recall exactly when Mr Tremaine first told her about Mr Scott’s alleged involvement in his brother’s death, but she was sure it happened.
"If I didn’t say anything I’d be the exact same as Tyler sitting there making it a topic or a conversation, it’s not ... you go to the police about it," she said.
Mr Tremaine said he never told the woman that Mr Scott threw Lachie in the pond and claimed he agreed with her to end the conversation.
"What [the woman] has said that I said to her isn’t true. I know the screenshots look bad but it’s not the case," the witness said.
"I don’t recall having that conversation with [her] in person, and Johnny never told me that."
Mr Tremaine said despite him and Mr Scott being good friends, they only discussed Lachie’s death once.
"Johnny said ‘you’ve never met my brother ay? Haha you won’t because he’s dead’," Mr Tremaine told police.
Mr Scott did not recall saying this.
Under cross-examination from Max Simpkins, counsel for Lachie’s father Paul Jones, Mr Tremaine admitted initially lying to police about the messages.
He initially stated he never spoke to the woman about Mr Scott or Lachie, but when presented with the messages said he did send them.
Mr Tremaine also deleted the messages from his phone before giving it to police, but was upfront about that when police queried it.
He could not think of a reason why the woman would make up the allegations, but said she could be problematic.
"I don’t want to be involved in this s...," he said.
"I don’t take this seriously. It’s got nothing to do with me."
He said if he had any relevant information about Lachie’s death, he would not hesitate about telling police.
The inquest will hear the lawyers sum up the case today.
