First appearance of Senator Carson, played by John Hart (1917-2009), a man with impeccable Texas creds: He played The Lone Ranger for the 1952-53 season. While this was Hart's fifth series appearance, it was his first as Senator Carson, a role he would play in three more episodes.
The title is based on the biblical account in Genesis 4 of the curse of Cain and the mark of Cain, in which God declared that Cain, the firstborn son of Adam and Eve, was cursed for murdering his brother, and placed a mark upon him to warn others that killing Cain would provoke the vengeance of God.