In 1933, Weiss married Yvonne Louise Pavy of Opelousas, the seat of St. Landry Parish. The couple had one son, Carl Austin Weiss Jr., who was born in 1934, shortly before the elder Weiss's death. Pavy was the daughter of Judge Benjamin Henry Pavy and Ida Veazie. The Pavy family was part of an anti-Long political faction. Judge Pavy's brother Felix Octave Pavy, a physician in Leonville and Opelousas, had run for lieutenant governor in 1928 on an intraparty ticket, and had been defeated by Paul N. Cyr, a Jeanerette dentist who was endorsed by Long. Similarly, Judge Pavy, Weiss' father-in-law, was the Sixteenth Judicial District Court state judge from St. Landry and Evangeline parishes. He did not seek reelection in 1936, after Long had the legislature gerrymander the seat to include a majority of pro-Long voters within a revised district..
Murder of Huey Long
On September 8, 1935, Weiss confronted and shot Huey Long in the Capitol building in Baton Rouge. At 9:20 p.m., just after passage of the bill effectively removing Judge Pavy, Carl Weiss approached Long, and, according to the generally accepted version of events, fired a single shot with a handgun from four feet away. Long was struck in the torso. Long's bodyguards, nicknamed the "Cossacks" or "skullcrushers", responded by firing at Weiss with their own pistols, killing him; an autopsy found that Weiss had been shot more than sixty times by Long's bodyguards.
Alternate theories and denials of the assassination
In the years since the event, theories have arisen that Weiss did not actually murder Senator Long; with some speculating that Long was, in fact, killed by a stray bullet fired from the gun of one of his bodyguards.
Family denials
At the time, Weiss's wife and their families did not accept his guilt. Indeed, Weiss's parents indicated that he had seemed quite happy earlier on the day that Long was killed. Many people close to the family, as well as politicians of the time, doubted the official version of the shooting. Weiss's son, Carl Jr., an infant at the time of his father's death, has since vigorously disputed the assertion. In a 1993 interview on the NBC program Unsolved Mysteries, he proffered the assertion that Long was accidentally shot by one of his own bodyguards. Donald Pavy, a medical doctor and first cousin of Weiss's wife Yvonne Pavy, conducted a scientific study of the case and concluded in his book Accident and Deception: The Huey Long Shooting that Weiss did not shoot the governor-turned-senator. A Louisiana State University Professor, T. Harry Williams, wrote in his Pulitzer Prize-winning biography of Long:
Portrayal in literature
The character of Adam Stanton in Robert Penn Warren's fictitious All the King's Men is partially based on Weiss. In her 1993 memoir, Marguerite Young mentions the murder of Huey Long and how she used to dance with Weiss as a college girl at Louisiana State University.