Petillo competed in the Indianapolis 500 on ten occasions, winning the race in 1935 in a year that marked the first win by a car powered by an Offenhauser engine. Petillo went on to win the 1935 AAA National Driving Championship. In 1937, Petillo participated in the Vanderbilt Cup but engine problems forced him out of the race.
In 1942, Petillo sustained a concussion and lacerations after a road accident when his car collided with a freight train. Petillo was denied entry to the 1946 Indianapolis 500, and sued the Indianapolis Motor Speedway for $50,000.
Off the track, Petillo had numerous run-ins with the law, including charges of attempted rape and attempted murder. Police arrested him in victory lane after winning a race at Owosso Speedway, on charges of assault to commit murder seven days earlier. He was sentenced to ten years in the Indiana State Prison. He was released on parole in 1955, but went missing. He was re-captured in 1957, incidentally, at the Indianapolis Motor Speedway. He was returned to prison until 1959, after which he was denied entry to the Indianapolis 500 in 1959 and 1960, officially due to age. After his exclusion in 1959, he again filed a lawsuit for $50,000 against the speedway and the United States Auto Club.
Petillo died of emphysema in 1970.
Indianapolis 500 results
|Indianapolis 500 Winner
| Succeeded by|
- "The Talk of Gasoline Alley" 10780-WIBC, May 23, 2003
- Milwaukee Journal. "Kelly Petillo Is Ranked at Head of Auto Racers". December 22, 1935, p. III-4. Retrieved on May 23, 2015.
- Pittsburgh Post-Gazette. "Kelly Petillo Hurt, Car Crashes Train". April 13, 1942, p. 17. Retrieved on May 23, 2015.
- Milwaukee Journal. "Petillo Starts Suit Against Speedway". May 24, 1946, p. L-13. Retrieved on May 23, 2015.
- Milwaukee Journal. "Petillo Sought After Attack". June 30, 1948, p. L-7. Retrieved on May 23, 2015.
- Mitchell, Dawn (May 23, 2014). "Retro Indy: Kelly Petillo was a Indy 500 winner with a rap sheet". The Indianapolis Star. Retrieved April 22, 2015.
- Milwaukee Sentinel. "Increase Jail Term for Petillo". July 13, 1957, Part 2-p.3. Retrieved on May 23, 2015.
- St. Petersburg Times. "Kelly Petillo Sues Speedway, USAC Again". May 26, 1959, p. 2-C. Retrieved on May 23, 2015.