He extensively detailed the last days and hours of Ms Asher's life and concluded that it was most likely that she had wandered into the surf and drowned.
Mr Sutton said there was no evidence she had been a victim of foul play.
It was also unlikely she had gone into hiding or become lost in the bush and died of exposure.
He also concluded that there were major shortcomings in the way police handled Ms Asher's 111 call, and the failure of Piha residents who found her in a disoriented state to call police.
He believed that had those residents called police, and had police sent a patrol car after Ms Asher indicated she felt unsafe - she may still be alive today.
Ms Asher's ex-boyfriend has also given evidence at an inquest into her death.
Julian Dyson was in a relationship with the Auckland model for about four years. However she broke up with him just before she died as she had started a new relationship with her flatmate's brother.
At the Auckland District Court this afternoon, Mr Dyson told Coroner Peter Ryan he did not believe Ms Asher would have taken her own life. He also said she was a conservative person who was unlikely to do reckless things, such as go swimming on her own in the dark.
He said she knew Piha well, was not afraid of the water and was a strong swimmer.
Mr Dyson said reports of Ms Asher's behaviour in the hours leading up to her death led him to believe she was suffering from a bipolar episode when she disappeared.
The inquest had also heard from the police officer who led a massive air, sea and land search in and around the Piha area - where the 25-year-old was last seen.
Senior Sergant Mark Fergus was the on call Search and Rescue controller for the greater Auckland area the weekend Ms Asher went missing.
His evidence is continuing, but he has outlined the planning and execution of different tasks given to search teams looking for Miss Asher.
Two associates of Ms Asher have also given evidence this afternoon, describing her behaviour in the lead up to her disappearance. Both witnesses applied to Coroner Peter Ryan to have their names and any information that would identify them suppressed.
The first witness wanted to protect herself and her child from unwanted media attention.
The second said Ms Asher's disappearance had resulted in him seeking medical treatment for depression and anxiety. He also wanted to protect the privacy of his family.
Both witnesses spoke of Ms Asher's "weird" and "sexually charged" behaviour and "extreme" moods before she vanished.
The inquest will continue tomorrow and members of Ms Asher's family are expected to give evidence.
The inquest continues.
