One of two men charged with the 2011 murder of a man whose body was found buried in an olive grove north of Adelaide has changed his plea to guilty.

Edward Camilleri, 50, was reported missing four months before his body was found at Two Wells, when he failed to turn up for the first day of a new job.

Steven Zenunin, 21, and Domenico Antonio Papalia, 30, were charged with his murder in March last year.

The pair have appeared before the South Australian Supreme Court where Zenunin's lawyer Grant Algie told the court his client would be changing his plea to guilty.

Prosecutor Jim Pearce told the court Zenunin is expected to be called as a witness during the trial.

Justice Michael David said he would hear sentencing submissions for Zenunin next Monday.