Duval, a 39-year-old former yoga instructor who was born Alison Dadow, has long maintained her innocence. On Monday, she sat somberly inside a Maui courtroom as the prosecution laid out its case against her.
Wearing a blue shirt and sporting bangs, Duval listened as Maui Deputy Prosecuting Attorney Emlyn Higa alleged that she deliberately steered her SUV towards the edge of a cliff, sending the car plunging 200 feet into the rocky shoreline below.
Duval has requested a bench trial, leaving her fate in Cahill’s hands.
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Severely injured, Duval survived the May 29, 2016, incident. The passenger, her twin sister Anastasia Duval (born as Ann Dadow), did not.
A motive remains unclear in the alleged murder, which Duval has twice been charged with; initial charges against her were dismissed for a lack of evidence.
The identical twins were born in Utica, New York, and formerly owned and operated yoga studios in Palm Beach County, Florida, and Park City, Utah. They had moved from Florida to Utah and then to Hawaii in 2015.
An ex-boyfriend of one of the sisters previously told PEOPLE the twins had a highly volatile relationship.
Higa said in his opening statement that Alexandria Duval allegedly “intentionally or knowingly” drove off the cliff as the sisters fought.
But Duval’s defense attorney, Birney Bervar, countered that the fatal wreck was an “accident, not murder.”
According to Higa, another driver, Randolph Castro, saw the Duvals’ SUV swerving about an hour before the crash. Other cars were forced to move out of the allegedly zigzagging vehicle’s path.
Higa said Monday that Castro followed the SUV, and allegedly saw the twins stop a few times. Eventually, Castro watched the sisters allegedly “physically fighting within the car,” Higa told the judge.
Castro attempted to figure out why the women were arguing when “the defendant just drove off again,” Higa said.
The prosecutor continued, telling the judge that another witness allegedly heard “screaming” coming from the SUV; the witness allegedly heard the driver yell three times about “needing a psychiatrist,” though it was unclear who Alexandria was allegedly referring to.
Duval, Higa said Monday, allegedly later stopped the SUV, and witnesses noticed the hazard lights flashing. The fight continued, according to the prosecutor, who claims a witness allegedly said he heard the SUV’s engine revving loudly before accelerating down the road, straight, until it “suddenly jerked” to the left and went over the cliff.
Higa told the judge the state’s case hinges on three alleged facts: He alleges there was a hard acceleration, a hard left turn and no braking. He said he intends to back up these claims with eyewitness testimony, data retrieved from the SUV, and evidence recovered from the roadway.
But Bervar argued in his opening statement the evidence from witnesses will prove Anastasia died as at the result of a “tragic accident.”
Bervar noted that Anastasia’s hands contained strands of his client’s hair, indicating Alexandria was being violently attacked and, as a direct result, lost control of the vehicle.
He said that “several eyewitnesses” saw the violent interaction, and will testify “the passenger was violently pulling my client’s hair with both of her hands — pulling it so hard it was jerking her head over the passenger side seat.”
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On Monday, a police officer took the witness stand and testified that the SUV sustained heavy damage when it collided with the rocks, and that when he got to the vehicle, the passenger was foaming at the mouth and seemed to have “major head trauma.”
The officer also alleged Alexandria had alcohol on her breath.
The trial is set to resume today in Maui.
PEOPLE’s attempts to reach Higa and Bervar were unsuccessful Tuesday morning.