The police officer who led the investigation into Liam Fee's death has said the two-year-old was subjected to "horrendous abuse" at the hands of his mother and her partner.
Detective Inspector Rory Hamilton praised the bravery of two other boys, whose evidence meant Liam's mother, Rachel Trelfa or Fee, 31, and Nyomi Fee, 29, were convicted of the youngster's murder.
The two women had blamed another child for killing two-year-old Liam, with Mr Hamilton, of Police Scotland's major investigation team, stating: "Details of Liam's murder and the abuse carried out by the two women emerged during the course of interviews with two other boys in their care.
"During joint interviews with specially-trained detectives and officials from Fife Council, the evidence began to build towards a picture of horrendous abuse which directly contributed to the version of events being put forward by the two accused being utterly discredited.
"This was a complex, challenging and sensitive investigation which involved interviewing two young children to establish the level of abuse and neglect both they and Liam Fee had been subjected to.
"It was because of their courage that detectives were able to identify Rachel and Nyomi Fee as being responsible for a wide range of serious offences against three children."
Assistant Chief Constable Malcolm Graham, lead officer for major crime and public protection, said: "Liam's murder has had a profound effect on everyone involved in the investigation and our thoughts are with his wider family.
"The death of a child is always traumatic but the murder of a child has a terrible and lasting impact on the family, on the wider community and on the carers and professionals involved."
Matt Forde, national head of service for NSPCC Scotland, said Liam and the two other boys involved had been "the subject of the most horrific and long-term abuse by a couple who should have loved and nurtured their family, but who instead brutally murdered a child in their care".
He added: "Everyone who has followed this case will have been deeply affected by the accounts of neglect, cruelty and violence inflicted on Liam during his short and tragic life.
"The details of how this couple submitted young children to such abhorrent abuse have rightly shocked the public, yet sadly cases of abuse and neglect are taking place every day in homes across the country, damaging the futures of many children.
"Babies and young children are completely reliant on others and we all must look out for their welfare.
"We need to be alert to the signs that a child may need help and be ready to take action to protect them."
Social Work Scotland president Elaine Torrance said Liam's death was "an absolute tragedy" after he suffered "deeply shocking" abuse.
Ms Torrance said: "What makes it worse is that the abuse was carried out by the very people Liam should have been able to trust the most: his mum and his step-mum.
"Cases like these are exceptional and children dying at the hands of their parents remains a rare occurrence in Scotland.
"Parents are the primary protectors of their children and when that relationship fails and where people go out of their way to keep agencies at arm's length, children can be at terrible risk."
Fife Council will continue with a significant case review to discover if more could have been done to help Liam, she added.