Ex-Boyfriend of 'Yoga Twin' Sheds Light on Their Volatile Behavior: 'Do That Again, You're Dead'

Jeffrie Hall says the twins were often out of control and exhibited volatile mood swings.

The ex-boyfriend of the yoga instructor allegedly killed by her identical twin sister in Hawai is speaking out.

Jeffrie Hall recalled to Inside Edition how he told slain sister Anastasia Duval and her twin not to drive near a steep cliff in Hawaii in June 2016, making an eerie prediction.

Read: Twin Killing: Woman Charged With Murdering Her Identical Sister in Latest Twist of Their Bizarre Lives

“I told them if they went out there they would get into a fight and go over a cliff,” he said.

Alexandria Duval, 37, is accused of killing Anastasia by intentionally driving their car over a steep cliff in Hawaii.

Witnesses say the twins were seen arguing in their car as they headed down a treacherous stretch of the Hana Highway in Maui. Just before the car went over the cliff, the witnesses saw hair-pulling and fighting over the steering wheel.

In December, Alexandria pleaded not guilty to murder charges.

Inside Edition asked Hall if he believed Anastasia’s death was an accident.

“I know it was just an accident," he said. "There was no intent to drive off a cliff and kill her sister."

He added: "This isn't a murder; there’s no way this is murder. How can it be murder if you drive off a 200 foot cliff? There's no assuring yourself that you are going to make it out of there."

He hopes prosecutors putting Alexandria on trial eventually see it the same way.

“She's been through enough, she has to deal with not having her sister, the one who finishes her sentences and knows where the other half of everything is,” he said.

Hall says the twins were sometimes out of control with volatile mood swings. He had even recorded video of Anastasia, which he claims he did to prove she had a drinking problem.

In the video, Hall can be heard saying, "Look at you, you're wasted."

She responds: “No, I am not.”

When Anastasia discovers he is recording her, she threatens him and angrily reacts to what he is doing.

“Do that again. You're dead,” she said.

He replied: “Do what again?

“Take a picture of me,” she said. “Never take a picture of me again."

Hall recalled a story about how he once mistook Alexandria for her identical twin.

“I get woken up by what to what I thought was Anastasia, sobbing, rocking topless, so, I’m like, ‘It's ok, it’s ok, it’s ok.’ [Then] Anastasia walks in, so here I am hugging her topless sister and she's like, 'What you are doing?'"

With piercing blue eyes and striking blond hair, the twins made quite a statement as yoga instructors in Palm Beach, Florida, and Park City, Utah.

Hawaii was supposed to be a fresh start, but wherever they went, trouble followed. Hall says the twins had a tumultuous relationship — best friends one moment, fighting the next.

Read: Ex-Boyfriend of 'Yoga Twin' Speaks of Sisters' Violent Tempers: From 'Jekyll to Hyde'

He recalled: “They're like going at it and I like try to break it up and Anastasia just stops and looks at me and says in a really deep voice, 'If we are fighting, just let us fight.'"

Hall, who drives a cab, says he's not too surprised that the twins ended up going over a cliff because the same disaster almost happened to him when he was driving with his girlfriend.

“She took my taxi meter thing and ripped that off,” he recalled. “So, I’m like, ‘I got to get off the highway’ and I go to make a left turn, she put her hands on my steering wheel and I almost hit the curb.”

Alexandria is due in a Maui court on January 26, her bail has been set at $3 million. 

Watch: Twin Charged for Murder Again After Driving Off Cliff in Crash That Killed Her Sister