Read here: https://www.imdb.com/name/nm0912001/bio ... _ov_bio_sm
He was born in 1920.
Excerpt (slightly edited for brevity): "young Jack Lebzelter was expelled from ((High School)) for repeatedly fighting. Good with his fists, he turned professional, boxing as a welterweight under the name 'Johnny Costello', adopting his mother's maiden name. The purses were poor, so he soon left the ring ((...)) before signing up with the U.S. Navy in 1938."
https://boxrec.com/en/proboxer/304531