THE mother who found her baby's coffin empty after 42 years has written to Police Scotland and the Crown Office to ask if any criminal charges are likely to be brought.

Lydia Reid, 68, discovered her son's coffin was buried in 1975 with no body in it.

She had been granted a court order for an exhumation at his burial plot in Edinburgh in August, but a forensic team -- including renowned forensic anthropologist Prof Dame Sue Black -- found no human remains.

A police inquiry was launched but it was reported in the BBC that she said there was a "lack of progress".

The Crown Office told the BBC it would be inappropriate to comment during the investigation.

In September, First Minister Nicola Sturgeon pledged to help Ms Reid in her quest for answers, giving assurances to see what assistance the Scottish Government could offer.

Ms Reid's son Gary died at seven days old at the city's Royal Hospital for Sick Children in July 1975.

In her investigation, Prof Black found wool, cotton and a little cross, all preserved incredibly well, in the plot at Saughton Cemetery.

However her report said that the coffin had been buried without human remains.

After details of this emerged, Police Scotland said detectives were trying to establish if any criminality had occurred.

Both NHS Lothian and Scotmid Funerals said they were giving their full co-operation.