To the general public he is most known for the hit single "Ballad of the green berets"
After his musical career he decided to write a series of novels centered around the character "Casca Rufio Longinius" Who is cursed for piercing Jesus on the crucifix with a spear and is forced to forever remain a soldier until the Second Coming of Jesus Christ.
In the mid 1980s Sadler moved to Guatemala City where he was shot in the head one night in a taxi. He spent 7 months in a coma and died more than a year later.