And police concede they could have been more careful in investigating the 3-year-old’s death, including establishing a more clear leadership structure.
Coroner Alexander Ho’s inquest into the 2019 death of the toddler continued in Invercargill yesterday.
Police formed the view Lachie had drowned after he was found face up in a Gore oxidation pond, but later admitted they "missed steps" in the investigation.
Lachie’s father, Paul Jones, called the investigation a "bloody botched-up police job" and said the conclusion that his son drowned lacked common sense.
Yesterday, it became clear police involved in the investigation did not agree on who was the officer in charge.
Counsel for Snr Sgt Fairley, Susan Hughes, KC, put it to Sgt Tamariki that he was "calling the shots" and information relating to the investigation was directed to his shared folder.
"I wouldn’t use the term ‘calling the shots’," he replied.
"I was of the belief I was not the head officer in charge of the investigation."
Snr Sgt Fairley gave evidence that Sgt Tamariki wanted to be in charge of the investigation as it was a development opportunity for him. Sgt Tamariki denied that was the case.
Snr Sgt Fairley admitted she had learned lessons from investigating Lachie’s death, including that the leadership structure should have been more clear.
"I could be more proactive in supervising some staff," she said.
Snr Sgt Fairley said police concluded that Lachie’s death was not suspicious on the night of his death.
"Was that view too hasty?" counsel assisting the coroner Simon Mount, KC, asked.
"I wouldn’t say hasty ... we still had inquiries to do, but from what was immediately in front of us, the right decision was made," the witness replied.
Mr Jones never accepted the conclusion that his son had drowned.
He said he never saw Lachie climb and he did not like to go very far on his own.
The witness explained he tried taking Lachie on his courier run, but said it was a "disaster" as he had to be carried most of the time.
"He was a lazy little prick," Mr Jones joked.
The witness said in the early stages of his relationship with Lachie’s mother, Michelle Officer, he treated her children as his own.
He admitted he would get drunk and yell at Cameron and Jonathan.
"I take full responsibility for it ... I have, on numerous occasions, roared at those boys," Mr Jones confessed. "I did get very hot-tempered."
Sgt Tamariki gave evidence that Mr Jones faked an injury after being arrested for assaulting Lachie’s mother.
"Mr Jones had earlier fabricated an injury to avoid being held in police custody," the witness said.
He explained he took Mr Jones to the doctor, who told the sergeant he believed the man was "faking" the injury.
"I made it clear to him that I was unhappy he had wasted police time," Sgt Tamariki said.
He recalled the rest of the car ride being silent, but Mr Jones said he raised concerns about Lachie living with Ms Officer and her sons.
"If that was said, I have no recollection of hearing that," Sgt Tamariki said.
"You can’t recall this information because it reflects poorly on you as a police officer, doesn’t it?" Max Simpkins, counsel for Mr Jones, stated.
"I would say that’s an incorrect statement," the witness replied.
Sgt Tamariki will continue giving evidence today.