Fr Rene Robert begged in an official legal document written in 1995 that whoever murdered him should be spared the death penalty.
The priest, who served in St Augustine, Florida, appeared to predict he would be killed during his work with convicts and mentally ill people.
Last year Steven Murray was charged with Fr Rene's murder after the accused led police to this corpse in woods in Georgia.
It was later revealed the priest had been attempting to help Steven Murray for months before he was killed.
In a document titled "Declaration of Life", Fr Robert wrote in 1995: "I request that the person found guilty of homicide for my killing not be subject to or put in jeopardy of the death penalty under any circumstances."
Prosecutors have been calling for the death penalty if Steven Murray is found guilty of murdering the priest but bishops delivered a 7,400-strong petition outside court urging judges and jury to honour his wishes and spare him capital punishment.
According to WALB News, Steven Murray told the court: "If anybody loves Father Rene, they'll forgive me because he was a man of God, and forgiveness is forgiveness.
"I have mental problems and I lost control of myself. I apologise."
