A man and woman wandered into the empty Cathedral at 10.30am on September 10 and stole the crucifix. After covering it with a coat, they placed it in a suitcase and wheeled it out of the Cathedral.
The theft was reported to SA Police later that day after a sacristan noticed the crucifix was missing when he was checking the security camera footage.
While the value of the approximately one-metre high crucifix is unknown, its presence in the Cathedral most likely dates back to 1954 when the Lady Altar was constructed.
Cathedral Administrator Fr Anthoni Adimai said the crucifix had immense spiritual significance to worshippers in the Cathedral, especially the many people who lit candles at the altar for loved ones and prayed to the Blessed Virgin Mary.
The security cameras clearly captured the man and woman approaching the altar, removing the crucifix from its place in the middle of several candles.
The footage can be viewed here.
Anyone who recognises the individuals, or has information that may assist the police investigation, is asked to contact Crime Stoppers on 1800 333 000 or report on line at www.crimestopperssa.com.au. They can remain anonymous.