Michael Hutchence was coward-punched a few years before his death. He was never the same.

Content warning: This article deals with suicide and may be triggering for some readers.

The new documentary Mystify: Michael Hutchence explores the turbulent life of the INXS lead singer and founding member.

The new film sheds light on a vicious attack that happened five years before Hutchence died in 1997.

On November 22, 1997, the body of the then 37-year-old was found in a Double Bay hotel room where he had reportedly ended his own life.

To this day, it remains one of Australia’s most talked about celebrity deaths.

The new documentary, which premiered at the Tribeca Film Festival in New York this week, explores the attack, which occurred in 1992, as being a catalyst for the INXS singer’s depression.

In the film, made by Australian filmmaker Richard Lowenstein, Helena Christensen, who dated the singer for four years in the early 1990s, describes the assault against the singer by a Copenhagen taxi driver.

The singer was king-hit by the man and as Christensen recounts, the attack was the origin of his fatal demise. The hit saw Hutchence fall to the concrete ground where he severely hit his head, and consequently suffered from brain damage.

The then-girlfriend of Hutchence said prior to the assault, the singer "seemed so joyful", but after the injuries "a dark, angry side came out".

"Things got very heavy in his head," she continued. "He didn’t seem himself."

He spent a month in his apartment, "throwing up blood and pushing away all food". The brutal attack was also the cause for the singer losing his senses of smell and taste.

"Helena had never spoken about that accident," said director Lowenstein to the audience at the Tribeca Film Festival after the screening, according to New York Post.

"It’s never been really looked at in how profound that was in changing Michael’s life and what happened at the end. She kept quiet for very personal reasons… It was kind of amazing to get that firsthand account of it."

Side note - Mandy Nolan, who was engaged to Michael Hutchence's brother, talks about the INXS' singers death in No Filter.

This isn't the first time the attack has been spoken about in terms of being a catalyst for the INXS rocker's decline in mental health.

In 2014, INXS's bassist Garry Beersan spoke to Channel Seven's Sunday Night about how the injury to Hutchence's head changed him.

"When Michael hit his head, he came back a different person and I'm sure doctors were prescribing all sorts of weird and wonderful concoctions," he told the program.

"He was a dick and it wasn't him, that's the thing. It wasn't the Michael we knew and that's what was so surprising. He couldn't smell, he couldn't taste, he was drinking wine by the bottle because it was just like nothing to him."

Mystify: Michael Hutchence will be released in Australian cinemas on July 4.