A significant case review into the death of a toddler murdered by his mother and her civil partner has found "missed opportunities across services" which could have "potentially prevented" the harm he suffered.
However, the independent review found Liam Fee's death "could not have been predicted" and the pair were "manipulative, devious and hindered services".
Rachel Trelfa, now 32, and her partner Nyomi Fee, 30, were jailed for life last July for murdering two-year-old Liam at his home near Glenrothes, Fife, on March 22, 2014, after subjecting him to more than two years of abuse and neglect.
He had suffered fatal heart injuries similar to those found on road crash victims and spent the last few days of his life in agony from an untreated broken leg and fractured arm.
The pair - originally from Ryton, Tyne and Wear - were also behind a catalogue of cruelty against two boys in their care.
Their trial at the High Court in Livingston heard a number of people had raised concerns about Liam's wellbeing with social services, including staff at a nursery he attended.
Liam is referred to as Child C in the report, which has not been published in full due to protection concerns.
The review, on behalf of Fife Child Protection Committee by Dr Jacqueline Mok, found: "While the death of Child C could not have been predicted, there were missed opportunities across services to intervene to provide support to the family.
"This may have led to a better understanding of the treatment of the children living within the home and could potentially have prevented the harm Child C suffered at the hands of his mother and her partner, which subsequently led to his death.
"However, it must be understood that in many ways the manipulative and devious nature of the mother and her partner hindered this from happening."
Liam was "not seen as a child in need of protection" against the backdrop of his mother and her partner's controlling behaviour, the report states, with staff lacking professional curiosity as explanations given by Fee and Trelfa were at times accepted without challenge.
There were missed opportunities to uncover the abuse at child protection interventions instigated after a childminder and nursery staff noticed Liam had injuries, as his mother's explanation that he was self-harming was accepted and at the first intervention no paediatric advice was sought.
The report states: "Had all the concerns been taken into account, the balance of probability would have led to the conclusion that the injuries and concerns were likely to be the result of abuse."
Evidence was found that gaps in information-sharing and planning between agencies led to an "inability to recognise potential harm" to Liam.
Twenty recommendations have been made, including considering having mandatory child protection training for GPs and ensuring all children with concerning injuries are examined by paediatricians.
Alan Small, chair of Fife's Child Protection Committee, said: "We deeply regret that our services did not do more to support Liam and potentially prevent the tragic outcome of this case."
He added: "The results of the significant case review paint a picture of services that struggled to see through the actions of devious and manipulative parents.
"There were missed opportunities across services to intervene and provide support to the family, and services are aware that they could have done better to support Liam.
"It's clear that professionals who were making strenuous efforts to act in Liam's interests were drawn in by the demands and needs of Liam's mother and her partner, who were adept at playing the system, using 'disguised compliance' to play one professional against another."
He said all agencies involved accept the findings and said the recommendations are either being taken forward or are already in place.
Social Work Scotland vice-president Jackie Irvine said: "The fact that the report states Liam's death could not have been predicted does not mean we have nothing to learn.
"This report will be analysed by all of us who work in child protection, to make sure we understand how to improve things in our areas too."