Carl Austin Weiss Sr. (December 6, 1906 – September 8, 1935) was an American physician who assassinated U.S. Senator Huey Long at the Louisiana State Capitol on September 8, 1935.

Weiss was born in Baton Rouge to physician Carl Adam Weiss and the former Viola Maine. Weiss's father was a prominent ophthalmologist who had once treated Senator Long.^[1] His family was Catholic; his father was of German descent and his mother had French and Irish ancestry.^[2][3][4] Weiss was educated in local schools and graduated from St. Vincent's Academy.^{[citation needed]} He then obtained his bachelor's degree in 1925 from Louisiana State University in Baton Rouge. He did postgraduate work in Vienna, Austria, and briefly practiced at the American Hospital of Paris.^[5]

Weiss thereafter was awarded internships in Vienna and at Bellevue Hospital in New York City. It was while in Europe that Weiss bought a FN Model 1910 pistol for $25 (equivalent to approximately $146 in 2023^[6]) that he allegedly used in the Long assassination.^[7]

In 1932, he returned to Baton Rouge to enter private practice with his father. He was president of the Louisiana Medical Society in 1933 and a member of the Kiwanis International.^{[8][clarification needed]}

On September 8, 1935, Carl Weiss confronted and shot Huey Long in the Capitol building in Baton Rouge.^[9] At 9:20 p.m., just after passage of a bill reconfiguring the district of Weiss's father-in-law, Judge Benjamin Henry Pavy, to deny him reelection, Weiss approached Long. According to the generally accepted version of events, Weiss fired a single shot with a handgun from four feet (1.2 m) away. Long was struck in the torso. Long's bodyguards, nicknamed the "Cossacks" or "skullcrushers",^[10] responded by firing at Weiss with their own pistols, killing him; an autopsy found that Weiss had been shot more than 60 times by Long's bodyguards.^[10][11]

As both Long and Weiss died before a trial could be held, the claim that Weiss was Long's assassin was never proven in court. Additionally, no autopsy was ever performed on Long. 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.^[12]

With the approval of the family, the remains of Weiss were exhumed in 1991 and examined by James Starrs to attempt to determine if Weiss was the actual killer of Long.^{[clarification needed]} Starrs was also the publisher of the Scientific Sleuthing Review.^[17]

The character of Adam Stanton in Robert Penn Warren's fictitious All the King's Men is partially based on Weiss.^{[citation needed]}

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.^[18]

Nobel laureate Ernest Hemingway suffered a severe gash to his forehead when a skylight fell on him in March 1928 in his Paris apartment.^[19] He was treated at the American Hospital of Paris, and it took nine stitches to suture his head wound.^[20] He was left with a permanent, prominent scar on his forehead.

Later in life, Hemingway claimed that the physician who treated him was Carl Weiss. However, Hemingway was almost certainly mistaken, as Weiss did not start practicing at the hospital until July 1929, sixteen months after Hemingway was treated for his head wound.^[21]