Lisa Lines is accused of being the woman at the centre of a violent love triangle that came to a head in a gruesome incident in the Adelaide Hills in October 2017.
The 43-year-old's ex, Jonathan Hawtin, was rendered tetraplegic - paralysed from the neck down - after being struck repeatedly in the neck with a hatchet while Lines' then-partner Zacharia Bruckner was shot in the abdomen.
Mr Hawtin, 36, was charged with attempted murder for shooting Bruckner, 30, with police assuming the younger man was acting in self-defence.
However, a jury of six men and six women unanimously acquitted Mr Hawtin in 2019 after three hours of deliberation.
During the trial, the jurors had heard Lines in June 2017 told Mr Hawtin, with whom she had two children, that she wanted wanted to separate. She began a romantic relationship with Bruckner in August that year.
The court was also told Lines had a relationship with another woman and the pair discussed suffocating Mr Hawtin as he convalesced in hospital.
The other woman was spotted at his rehabilitation centre on New Year's Day 2018, the jury heard.
In 2020, SAPOL's Major Crime Investigation Branch reopened the investigation, resulting in a warrant being issued for Lines' arrest.
On Wednesday, police in the Pacific Island nation of Palau arrested Lines and remanded her in custody ahead of her expected extradition to South Australia.
Bruckner was arrested in Brisbane on Wednesday on conspiracy to murder offences.
The pair are accused of attempting to murder Mr Hawtin in the October 2017 incident as well as co-conspiring to murder Mr Hawtin and his mother Rhonda Hawtin between December 2021 and August last year.
Lines is also charged, along with the other woman, with attempting to murder Mr Hawtin on New Year's Day 2018.
Bruckner faced a Queensland court on Thursday, where detectives were granted an extradition order to take him to SA.
Police have not ruled out further arrests or charges in relation to the incident.
