Kimberley Hainey was sentenced to life behind bars in 2012 for killing her son Declan after his mummified remains were found in his litter-filled cot a month before his second birthday.
She was released last April on appeal after evidence at her trial was ridiculed by a judge - prompting the Crown Office to call for a Fatal Accident Inquiry to try and establish how Declan died.
Hainey was originally cited as a witness ahead of the inquiry, which began at Paisley Sheriff Court last week.
But, before the FAI got under way, a revised witness list was submitted by the Crown - removing Hainey.
Instead of the 39-year-old giving evidence in person, the evidence she gave during her murder trial has been typed up and is available to those involved in the case in transcript form.
If new evidence emerges during the FAI, Hainey could, due to reforms made in 2011, be tried again.
A Crown Office spokesman said: "There is no immunity from prosecution."
Hainey - who is now thought to be living in Fife - spoke publicly for the first time about the case in March this year.
Photographs of the state of Hainey's house, taken after Declan was found dead in his cot, shocked the nation.
But Hainey has insisted her son didn't live in those conditions, saying he had died and she struggled to cope with what had happened.
The decision not to call Hainey to give evidence has been ridiculed by legal insiders.
One said: "Hainey lied to everyone, so asking all of them what happened can't reveal what went on.
"Not calling her to give evidence is nothing short of ridiculous."
A Crown Office spokesman said they do not discuss witnesses in ongoing criminal cases or Fatal Accident Inquiries.
The FAI continues.