The ankh (key of life) was commonly held in the hands of ancient Egyptian deities, or being given by them to the pharaoh, to represent their power to sustain life and to revive human souls in the afterlife. The ankh was one of the most common decorative motifs in ancient Egypt and was also used decoratively by neighbouring cultures. Coptic Christians adapted it into the crux ansata, a shape with a circular rather than oval loop (as seen in the image above), and used it as a variant of the Christian cross. The message of "Satan Saves" rather than "Jesus Saves", along with a crucifix style cross, gives the strong impression of a murder with religious connotations, bearing in mind the anti-gay and intolerant Christian attitudes that permeated society in 1970 (and to a lesser extent today). Robert Salem was a gay man, who may have unfortunately attracted somebody with the belief he was a sinner or non-believer - and hence the sarcastic message of "Satan Saves" and the "key of life" being drawn on his stomach. Clearly, the person who drew the symbol and writing, was portraying a message to the viewer (whether a belief sincerely held or not).
The most unusual and notable features inflicted to the body of Robert Salem, were the crucifix style design "drawn" on his stomach and the removal of his left ear. Both of these featured heavily in the crucifixion of Jesus. Simon Peter, a disciple of Jesus, attempted to "save" and protect Jesus from arrest by severing the ear of Malchus, who was a servant of the Jewish High Priest Caiaphas. According to the gospels, Calaphas organized a plot to kill Jesus. The arrest of Jesus was a pivotal event in Christianity recorded in the canonical gospels. It occurred shortly after the Last Supper (during which Jesus gave his final sermon), and immediately after the kiss of Judas, which is traditionally said to have been an act of betrayal since Judas made a deal with the chief priests to arrest Jesus. This event ultimately led, in the Gospel accounts, to the crucifixion of Jesus. Although the right ear of Malchus was severed, as opposed to the left ear of Robert Salem, this was the most viable connection I could find that links the two unusual features discovered by investigators on the body of Robert Salem.
ROBERT SALEM-A ZODIAC MURDER?
A CONTEMPORARY CODE ON APRIL 20TH 1970
THE ZODIAC KILLER-DRIVEN BY DEVIANCY
A SATANIC MESSAGE IN CODE?