Hosting a 40-minute sit-down press call after the screening of the new Matt Damon family drama Stillwater at the 74th Cannes Film Festival on July 9, an Italian journalist asked the one question on everyone’s minds.

Was Stillwater’s storyline based on the so-called “Amanda Knox saga“, the American student who was convicted – and then acquitted – of the 2007 murder of British exchange student Meredith Kercher in Italy?

Oscar-winning Spotlight director and co-writer Tom McCarthy replied: “I was pretty fascinated with the Amanda Knox case back a long time ago and did a pretty deep dive into it, tracking it and keeping up to speed.”

“But … it really just served as inspiration at that point,” McCarthy said.

Knox, 34, 2013 best-selling author and host of the Labyrinths podcast (The Truth About True Crime), returned fire and criticised the film in a lengthy Twitter tirade, venting her frustration as to why she continues to “bear the infamy of Meredith Kercher’s tragic death”.

Tweet from @amandaknox

“This new film by director Tom McCarthy, starring Matt Damon, is ‘loosely based’ or ‘directly inspired by’ the ‘Amanda Knox saga’, as Vanity Fair put it in a for-profit article promoting a for-profit film, neither of which I am affiliated with,” she wrote.

“Everyone else in that ‘saga’ had more influence over events than I did. The erroneous focus on me by the authorities led to an erroneous focus on me by the press, which shaped how I was viewed. In prison, I had no control over my public image, no voice in my story.

“This focus on me led many to complain that Meredith had been forgotten. But of course, who did they blame for that? Not the Italian authorities. Not the press. Me! Somehow it was my fault that the police and media focused on me at Meredith’s expense.”

Knox also spoke to CNN and wrote a first-person piece on the issue in The Atlantic, saying the makers of Stillwater should have contacted her, and are profiting from her struggle over her wrongful conviction.

“Anyone who is watching this film is going to recognise me in it,” she said.

Damon, and Abigail Breslin, who plays his imprisoned daughter in France, in Cannes in July. Photo: AAP

What exactly happened in Perugia in 2007?

By all accounts, it was the crime story of the decade as British, US and Italian media outlets were captivated by what happened in that Perugia apartment on November 1, leaving one girl dead, one accused of murder.

Knox, then 20, shared Via della Pergola 7 with Ms Kercher, 21, but had been spending time with then boyfriend Raffaele Sollecito, a 23-year-old software engineer student.

When Ms Kercher didn’t answer her phone on the morning of November 2, Knox and Mr Sollecito, returned to the apartment, discovering bloodstains in the house and her bedroom door locked.

They called police, and found Ms Kercher on the floor. She had been raped and her throat was cut.

What happened next was everyone’s worst nightmare in a foreign country.

Knox (not fluent in Italian or having any understanding of the Italian legal system) and her then-boyfriend were twice convicted of killing Ms Kercher.

The Ivory Coast-born Rudy Hermann Guede, who had been living and socialising with the group at the time, was convicted of conspiracy to commit murder and rape in a separate trial and sentenced to 16 years.

He was released last year.

Knox at a Criminal Justice Festival at the University of Modena in Italy. Knox is speaking out about her name being associated with Stillwater. Photo: AAP

Knox and Mr Sollecito were exonerated in 2015.

“I want to pause right here on that phrase: ‘the Amanda Knox saga’. What does that refer to? Does it refer to anything I did? No. It refers to the events that resulted from the murder of Meredith Kercher by a burglar named Rudy Guede,” Knox said.

“It refers to the shoddy police work, prosecutorial tunnel vision, and refusal to admit their mistakes that led the Italian authorities to wrongfully convict me, twice. In those four years of wrongful imprisonment and eight years of trial, I had near-zero agency.

“By fictionalising away my innocence, my total lack of involvement, by erasing the role of the authorities in my wrongful conviction, McCarthy reinforces an image of me as a guilty and untrustworthy person.

“I have not been allowed to return to the relative anonymity I had before Perugia. My only option is to sit idly by while others continue to distort my character, or fight to restore my good reputation that was wrongfully destroyed.”

On her website, Knox, who is expecting her first baby with husband Christopher Robinson, wrote in December: “It has been my fate to bear the infamy of Meredith Kercher’s tragic death, an infamy that belongs to her forgotten killer: Rudy Guede.”

She was, as she said, “the innocent roommate”.

Damon stars as Oklahoma rough-neck oil rig worker who travels to Marseille to get his daughter out of prison. Photo: Twitter

So how much of Stillwater is ‘loosely based’ on Knox?

Knox’s story may have fascinated McCarthy – and a first look at the film does warrant solid comparisons – but he explains it’s so much more.

McCarthy told the Cannes press conference: “I started thinking of the relationship between a father, and I just had a daughter, and what that would be like for a man to travel and connect and the story sprang from there.

“It served as an initial inspiration point but not much more than that.”

In a recent Vanity Fair piece promoting the film, McCarthy said: “There were so many characters around the case that I really followed pretty closely.

“But really the first thing that I took away from it was, what would that be like as an American student to go over [to Europe] for what should be one of the most exciting moments in a young adult life and to find yourself in that tragedy?

“There were just so many layers to that story that kept anyone who was following pretty riveted … Who are the people that are visiting [her], and what are those relationships? Like, what’s the story around the story?”

There are differences.

Stillwater is based in Marseille, a port city in southern France; college student Allison (Breslin) is in jail for five years for a violent crime (no spoiler here), and she has no help from family, friends or the legal community.

McCarthy and his writers, listening to Serial podcasts and S-Town decided to “take this piece of the [Knox] story” and fictionalise the rest.

Added Damon in a separate VF interview, the exploration of the “fraught” relationship between father and daughter was where the movie ended up, stressing that Stillwater is “not an American film, not a French film, but a hybrid film”.

Stillwater opens in Australian cinemas on August 26