EXCLUSIVE: As Robert De Niro and director Martin Scorsese ready their splashy reunion mob drama The Irishman to world premiere at the New York Film Festival before Netflix releases its this fall, the actor and director are getting closer to jumping right back in with the Imperative Entertainment-produced Paramount drama Killers of the Flower Moon. De Niro is in early negotiations now to team with the director’s other most frequent collaborator, Leonardo DiCaprio.

An adaptation of the nonfiction book by David Grann, Killers of the Flower Moon tells the true crime story of multiple murders of members of the Osage Indian tribe in 1920s Oklahoma that occurred after they found oil on their lands.

Sources said that an offer is imminent and that, subject to a final budget being approved, they are clearing schedules for a movie that should be in production by the middle of next year. Deadline reported in 2017 that De Niro and DiCaprio constituted Scorsese’s dream cast for the film. Now it’s moving toward happening, and that would be two in a row for the duo whose classic collaborations include Mean Streets, Raging Bull, Goodfellas, Taxi Driver and Casino, but who haven’t made a movie together in nearly 25 years. In a meeting with Principal Chief Geoffrey Standing Bear of the Osage Nation this past weekend, Scorsese said De Niro would be playing the serial killer William Hale, the Osage News reported.

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Last month, Deadline reported that Paramount was set to finance and distribute Killers of the Flower Moon with a script by Eric Roth. The next step is to lock the actors in deals and set budget.

De Niro and DiCaprio previously worked together in 1996’s Marvin’s Room and 1993’s This Boy’s Life, latter of which was a breakout for the younger star. Imperative partners Dan Friedkin and Bradley Thomas acquired the project in a $5 million deal in 2016, before the publication of Grann’s book by Doubleday. Friedkin and Thomas are producing with Sikelia Productions’ Scorsese and Emma Tillinger Koskoff and DiCaprio’s Appian Way Productions.

The book is a murder mystery, set in 1920s Oklahoma, where the Osage Indians were granted revenue rights to oil discovered under their lands that was harvested by oil companies. Suddenly, they began to get murdered as did those trying to investigate. It came down to the newly created Bureau of Investigation, to overcome the corrupting influences from oil money and politics to solve the murder mystery, one that would bring the FBI to prominence.

Per the Osage News report, Scorsese and Chief Standing Bear spent 2 1/2 hours together on Friday at the Osage Nation campus. The gist of the meeting was how the Osage Nation could help with the filming.

“We want to make sure your people have everything they need, in terms of Osage artisans, Osage language … those people are still here in the community and would love to help,” Standing Bear said. Talks are ongoing with the State Film Office of Oklahoma to shoot in Osage County, the newspaper reported.