Leonardo DiCaprio's production company, Appian Way, has joined Shannon Kring's investigative documentary Nine Little Indians, which is about the abuses endured by the Native American children at a US boarding school.

The film, which has been in the making for almost a decade, has entered the post-production stage. It revolves around the nine Charbonneau sisters and their friends who were abused at the St Paul's Indian Mission School in Marty, South Dakota. The documentary will feature the long-drawn legal battle of the sisters that protracted for a period of almost two decades, challenging the Catholic Church for its heinous crimes. The film also focuses on a Northern Cheyenne Indian school cemetery's surveyor's search for additional graves that are unmarked.

Appian Way, which has earlier produced The Revenant and Killers Of The Flower Moon, joins with Red Queen Media and Terra Mater Studios for the film.

Filmmaker Kring is best known for her documentary End Of The Line: The Women Of Standing Rock. DiCaprio will serve as the documentary's executive producer along with author and public speaker Tony Robbins, Jennifer Davisson, George DiCaprio, Phillip Watson, Marc Gerke, Sophia Ehrnrooth, Wolfgang Knopfler, and Walter Kohler.