Leonardo Dicaprio persuaded Martin Scorsese to alter the script for 'Killers of the Flower Moon' two years into writing it.

The 'Taxi Driver' director teamed up with Eric Roth to pen the script for the film based on David Grann's 2017 book of the same name - which focused on the FBI investigation into the murders of Osage Native Americans in Oklahoma throughout the 1920s - with DiCaprio originally lined up to play head investigator Tom White.

However, Scorsese ended up completely overhauling the script and changing the story's focus to the character of Ernest Burkhart and his marriage to an Osage woman named Mollie.

After changing the script, Scorsese switched DiCaprio's role - giving him the part of Ernest - while Jesse Plemons took on the role of Tom White, who became a supporting character.

And it was DiCaprio who felt the story should be told from the Osage community's perspective instead of the bureau agents investigating.

Speaking to The Irish Times, the director said: “Leo came to me and asked, ‘Where is the heart of this story?’ I had had meetings and dinners with the Osage, and I thought, Well, there’s the story. The real story, we felt, was not necessarily coming from the outside, with the bureau, but rather from the inside, from Oklahoma.”

After changing the perspective, the legendary filmmaker met with 300 members of Oklahoma’s Gray Horse community.

He said: “I always said if I ever get involved with anything that has to do with indigenous people, I’d better know who the people are or, at least, feel comfortable with them as human beings."

Scorsese had his own concerns about making the movie "about all the white guys".

He told Time magazine: "After a certain point, I realised I was making a movie about all the white guys. Meaning I was taking the approach from the outside in, which concerned me."