Months after Kansas authorities confirmed they suspected no foul play in Cole Brings Plenty’s death, the “1923” actor’s family has publicly challenged the results of their investigation.

The deceased actor’s father, Joe Brings Plenty Sr., said he is still “fighting to find out” what happened to his son while speaking Sunday at the Red Nation Film Festival in Los Angeles.

“My boy, we have some work to do,” the Cheyenne River Sioux tribal leader said at the Beverly Wilshire event. “We want a full investigation done, a fair investigation, to find out what happened with Cole.”

Cole Brings Plenty was found dead April 5 after being reported missing by his family almost a week before when he did not show up for a Zoom meeting with his agent. He was 27.

Along with the call on Sunday for a “fair investigation,” Joe Brings Plenty Sr. talked about his son’s work as an activist, which he called “quite scary, because the Indian issue isn’t a popular issue.”

In May 2023, Cole Brings Plenty joined his uncle, fellow “1923” cast member Mo Brings Plenty, and other actors and advisors from the show in calling for Congress to investigate the federal government’s Native boarding school policies. Native children who were forcibly removed from their homes and enrolled in such schools throughout the late 19th and early 20th centuries suffered physical, sexual, cultural and spiritual abuse and neglect, according to the National Native American Boarding School Healing Coalition.

Joe Brings Plenty Sr. referenced the Missing and Murdered Indigenous Women movement — an activist effort in response to the pervasive issue of missing and murdered Indigenous women across North America — saying, “We have a system that looks the other way when it’s dealing with the Indigenous populations.”

The family and others have criticized the investigation by Kansas authorities, especially Lawrence police’s early decision to treat the actor primarily as a criminal fugitive rather than a person in crisis or potential victim — which “put a big target on him,” Joe Brings Plenty Sr. said at Sunday’s event.

“The people who knew him knew what kind of person he was,” he said, calling his son a “very special” and “very bright individual.”

Following a days-long investigation in partnership with the Johnson County Sheriff’s Office, Lawrence police on April 10 released a statement saying, “There is no indication of foul play in the death of Cole Brings Plenty.” Neither a cause of death nor any autopsy details were disclosed.

The night before the actor is thought to have gone missing, Cole Brings Plenty attended a concert at the Replay Lounge in Lawrence, Kan. During the show, witnesses said, his braids got tangled in a microphone cable and a patron attempting to free him cut his hair off without his permission.

After leaving the bar around 1 a.m. March 31, Brings Plenty allegedly went to a nearby apartment, the Lawrence Times reported. There, officers later responded to “reports of a female screaming for help,” the Lawrence Police Department said in an April 2 Facebook post.

“Lawrence Police have submitted an affidavit to the District Attorney for the arrest of Cole Brings Plenty after an incident Sunday morning at an apartment in Lawrence. We’ve identified him as the suspect, have probable cause for his arrest, and issued an alert to area agencies,” the department said in the Facebook post, adding that “the suspect fled before officers arrived.”

Police also said that traffic cameras showed Cole Brings Plenty leaving the city immediately after the incident. They did not reveal the identity of the woman involved, though a friend of the family confirmed she was not the same woman who cut off Cole Brings Plenty’s hair at the Replay Lounge.

On the same day the police said there was no foul play, the warrant for his arrest was recalled. A little over a week later, a Douglas County District Court judge ruled the affidavit in support of the warrant — which was never executed — remain sealed, according to court documents reviewed by The Times.

A spokesperson for the Johnson County Sheriff’s Office declined to comment on the death investigation “because of a court order.” A spokesperson for the Lawrence police did not reply to The Times’ request for comment.

Upon the April 5 declaration of Cole Brings Plenty’s death, the Cheyenne River Sioux Tribe — of which he was a citizen — called for “a full and thorough investigation into Cole’s disappearance and subsequent death” and said its attorney general would be contacting Kansas officials “to ensure this is accomplished.”

“Cole Brings Plenty, an Indigenous man, has tragically become another statistic in the alarming trend of violence against Indigenous people,” said an April Change.org petition demanding justice for the late actor.

The petition continued: “This personal story is not just about seeking justice for one individual; it’s about challenging a system that often overlooks the plight of our Indigenous brothers and sisters.”

On Sunday, a memorial slideshow — including photos from the set of “1923” — dedicated to Cole Brings Plenty played after Joe Brings Plenty Sr.’s speech.

“Who’d have ever thought that a young man from South Dakota, grew up in a place called Darkside, would be on a big screen?” the former Cheyenne River Sioux Tribe law enforcement officer said during his speech, choking up. “And he was just starting.”