Prosecutors said there was no evidence of crimes being committed at an orphanage where at least 400 children are thought to have been buried in an unmarked mass grave.
A BBC and Sunday Post investigation discovered they were buried in the cemetery plot between 1864 and 1981.
They were children from the nearby Smyllum Park Orphanage in Lanark, run by an order of Catholic nuns.
The Crown Office said it recognised the level of public concern.
But it said there was currently no evidence of criminal activity.
The Crown Office and Police Scotland said the position will be kept under review and "any allegations of criminality will be thoroughly and sensitively investigated".
The orphanage, run by the Daughters of Charity of St Vincent de Paul, was home to more than 11,000 children over the 117 years before it closed in 1981.
Former residents of the orphanage uncovered the burial plot at nearby St Mary's cemetery in 2003.
They were unable to discover the scale of the number of children buried there but incomplete orphanage death records estimated it at about 158.
The BBC research has now put the number at 400.
Research into death records of children who lived there showed that most died of natural causes, from common diseases such as tuberculosis, pneumonia and pleurisy.
Campaigners said the unmarked mass grave was left untended while just a few metres away the graves of the nuns were well maintained and marked with head stones.
Some former residents have alleged that they were abused by nuns at the home.
One of the men who discovered the overgrown unmarked grave was Frank Docherty.
He fought for two decades to reveal physical abuse which he said many former residents had suffered.
His widow Janet Docherty told the BBC: "The people higher up should be telling the families exactly what happened to these kids."
Smyllum Park Orphanage is one of the institutions being examined by the Scottish Child Abuse Inquiry.
Representatives of The Daughters of Charity of St Vincent de Paul gave evidence to the inquiry in June and said they could find no evidence of abuse.
In a statement, they said they were "co-operating fully" with the Child Abuse Inquiry and that they believed that was the "best and most appropriate forum for such investigations".
They continued: "...as Daughters of Charity our values are totally against any form of abuse and thus, we offer our most sincere and heartfelt apology to anyone who suffered any form of abuse whilst in our care".
Childcare minister Mark McDonald told the Scottish Parliament that the inquiry and the prosecution services were the proper channels for taking the matter forward.
In response to a question by SNP MSP Clare Haughey, Mr McDonald confirmed that at the time of the deaths there was no requirement for private burial authorities to keep a register of burial plots.
File on 4: The Secrets of Smyllum Park is broadcast on BBC Radio 4 on Tuesday 12 September 2017 at 20:00 BST. You can also catch up on the BBC iPlayer.
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