In “61 Bullets,” Austin filmmakers David Modigliani and Lucy Kreutz revisit the assassination of populist Louisiana politician Huey P. Long.

On Sept. 8, 1935, the former governor and then U.S. senator was shot in a marble hallway of the Louisiana State Capitol. Instantly, the senator’s bodyguards fired 60 bullets into Dr. Carl Weiss, the man officially designated as the senator’s assassin. Weiss’ instantaneous death meant he’d never be tried. His side of the story would never be told.

Nearly 80 years later, Modigliani and Kreutz spoke to members of the Weiss and Long families about the incident as well as historians and a forensics anthropologist who exhumed Weiss’ remains in 1992.

The 58-minute documentary’s interviewees include Dr. Weiss’ son, New York resident Dr. Carl Weiss Jr.; the alleged assassin’s sister-in-law, Ida Boudreaux; a Weiss cousin, Dr. Donald Pavy; and Russell Long Mosely, a great-grandson of Huey Long who favors his famous ancestor.

Yvonne Boudreaux, granddaughter of Ida Boudreaux, co-produced “61 Bullets” with Modigliani. It’s likely that her connection to the Weiss family and the Pavy family that Weiss married into helped the project gain extensive access to the doctor’s surviving relatives. Members of the Long family are much less present in the film. Mosely speaks for them almost exclusively.

Controversies and theories about the official assassination record are quite familiar to Louisiana residents. Also, a 1992 episode of NBC’s “Unsolved Mysteries,” featuring Carl Weiss Jr., covered the topic. “61 Bullets,” however, featuring new interviews, does a good job of retelling the story and rekindling the doubts about Weiss’ guilt.

Because Huey Long is among the most documented men in Louisiana history, “61 Bullets” contains many film clips and photos of the charismatic Kingfish as well as newspaper clippings and other documents.

Mosely talks about the many good things his great-grandfather, a man both beloved and hated, did to lift impoverished Louisiana into the 20th century. The film also covers Long’s lust for power and his corrupt, absolute rule of Louisiana.

“61 Bullets” most of all presents a case that Weiss may not be Long’s assassin. Weiss’ relatives, especially, express their disbelief that a brilliant young doctor, husband and father of a 3-month-old boy, would choose to end his life by committing such a public murder of a famous man.

Some extraordinary bits of history come forth. Following Long’s death, his critics mailed money and letters of congratulations to the Weiss and Pavy families. Ida Boudreaux says in a new interview that her father returned every penny of the blood-inspired donations.

Boudreaux also gets some of the film’s last words. “Seventy-five years is nothing in history,” she says. “It’s like a grain of sand. It’s just beginning to move.”