SA Police is offering $1 million dollar rewards as part of Operation Persist to help solve cold cases.
They want to hear from anyone with information about the unrelated deaths of two babies in 2004 and 2010.
11 month old Dylan Lindsay was found in Port Lincoln with abdominal injuries after a serious assault.
While 18 month old Lily Schettini died from acute blunt head trauma at Smithfield Plains.
A million will also go to anyone with information about the disappearance of 11 month old Darren Shannon who was taken from his father's crashed car in 1973.
Other rewards are also on offer for another six unsolved cases ranging from an organised crime hit to a mystery fatal poisoning.
An original reward of $200,000 to resolve the murder of Coober Pedy schoolgirl Karen Williams has been raised to $1 million.
Police Minister Pete Malinauskas says 'often the renewed public interest connected to rewards prompts people to share information they may have previously withheld or thought not to be relevant'.
Anyone with information about the unsolved murders of Michael Modesti in 2016, Annabel Strzelecki in 1998, Brian Underwood in 1991, Laula York in 1974, Colleen Adams in 1973 and Antonio Giorgi in 1970 could be eligible for $200,000 rewards.