Milang man Giuseppe Iannella was reported missing in 1975 and he hasn't been seen or heard from since.
At age 46, Mr Iannella, known as Joe, went missing sometime between February and August 1975 the exact timing of his disappearance is unclear.
This week - which is also National Missing Persons Week - marks 45 years since he was reported missing.
He has not made contact or been seen since this time, and police presume he has been murdered.
He was living with his wife and four children at the family dairy farm on Lake Plains Road. He has olive complexion and would be 91 today.
Excavations at the farm occurred in September 2006 as Major Crime Detectives searched for his remains or anything related to his disappearance, without success.
In March 2015, the state government announced rewards for information on 54 cold case murders would increase to a minimum of $200,000. Mr Iannellas case is included in this list.
When a murder or suspected murder is unsolved for a long time, or there is not enough evidence to identify or prosecute someone, the $200,000 reward is offered. This increases to $1 million for crimes against the state and the abduction or murder of children.
Police said anyone who believed the passage of time meant some murders are unlikely to ever be solved should think again, as increased police resources and better technology have proven otherwise.
If you have information which may help police investigating Mr Iannellas disappearance, contact Crime Stoppers on 1800 333 000 or online at www.crimestopperssa.com.au
For more information, visit www.crimestopperssa.com.au/case/giuseppe-joe-iannella/ or www.missingpersons.gov.au/who-missing/sa/iannella-giuseppe