A man facing a murder charge in the killing of a Florida priest has said he "lost control" and is "very sorry".

Steve James Murray, 28, told local TV stations that he had mental problems and had "lost control of myself" when he killed 71-year-old priest Father Rene Robert, and has asked for forgiveness.

"If anybody really loves Father Rene, they'll forgive me because he was a man of God and forgiveness is forgiveness," he said.

"I have mental problems, and I lost control of myself and I apologise."

When asked specifics about what he did, Murray did not respond.

Murray has been described as a "career criminal" and police have said Robert met him through his work with prisoners.

Murray was arrested on Wednesday after he was spotted driving Robert's Toyota Corolla and is now facing murder charges from Georgia authorities.

An autopsy of the body on Thursday found Robert, identified through dental records, was shot multiple times.

It is believed he was killed on the evening of April 12, 260 miles from where his body was found near Waynesboro, Georgia on Monday night.

After he was arrested, Murray was interviewed and led police to the site of the body.

Murray had been released from the Duval County Jail in Jacksonville on April 6, after being arrested on March 22 for operating a vehicle with a suspended license.

Before his body was found on Monday, the priest from Florida had not been seen since April 10 and was reported missing on April 12.

"Father Rene was such a loving person and he would do anything for anybody and most people would say the same thing and the fact that he was trying to help somebody and that person took advantage of him, that's what hurts the most," Linda Bertino of the St Bonaventure Secular Franciscan Fraternity, said at a vigil.