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.

Read more: Liam Fee - Mother and her civil partner found guilty of killing her toddler son

"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.

Read more: Concerns had been raised several times about welfare of Liam Fee

"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."

The Herald:

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."

Read more: Liam Fee - The boy with a cheeky smile who was subjected to horrific abuse

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.

The Herald:

"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."

Read more: Liam Fee - Jurors were in tears as images of toddler's body shown to court

Fife Council will continue with a significant case review to discover if more could have been done to help Liam, she added.

Read more: Young boys' courage helped unravel couple's web of lies

A Scottish Government spokeswoman said: "The death of Liam Fee was a tragedy and our sympathies go out to everyone affected by this terrible crime.

"Clearly the individuals responsible for the unlawful death of any child are the people convicted by the courts.

"However, the public will rightly expect that any wider issues which may emerge from this case would be learned and acted upon.

"We therefore welcome Fife Council's announcement of a significant case review.

"We have kept in close contact with the relevant agencies throughout and will monitor the progress of the review and consider any recommendations that emerge, once complete."

A campaign group opposed to the Scottish Government's plans to introduce a named person for every child said the case raised more questions about the controversial scheme.

Under the initiative, all children will have access to a named person such as a health visitor or teacher from birth to 18 to provide support and advice, but critics claim the scheme is invasive and will detract from targeted interventions.

Fife is one of a number of regions to have begun implementing the initiative, which is due to be officially established across Scotland at the end of August.

No to Named Persons (NO2NP) said: "In light of today's ruling, concerning a tragedy in an area where the Scottish Government claim the named person pilot scheme is 'working well', the public is entitled to ask if Liam Fee was not only a victim of his mother and her partner, but whether this universal scheme got in the way of the kind of targeted intervention we all wish had been used to save his life."

A spokeswoman for Fife Council said every child has always had "a point of contact for parents and professionals", but it was "not accurate" to say every child in Fife has had the equivalent of a Named Person since 2009 as the role has been "introduced incrementally".

Former Children's Panel member and SNP MSP Rona Mackay said: "It is deeply distasteful for any campaign group to politicise the tragic murder of a young child.

"The only people responsible for the death of Liam Fee are those convicted of his murder, attempting to use this death to score political points is insensitive and disrespectful."

Scottish Conservative shadow justice secretary Douglas Ross said: "This was an appalling crime against an innocent child whose short life was cut down by an incomprehensible act of evil by his own family.

"It is a desperately sad tale in which a combination of callousness and carelessness appears to have led to a boy's life being lost.

"There must now be an urgent examination of the facts that led to Liam's murder, especially how his case was allowed to 'fall off the radar' as the trial revealed.

"For there to be such significant concerns raised by his nursery, most would alarm bells to ring, yet nothing seems to have happened. That raises serious concerns about the system and the checks and balances that take place.

"Sadly there is no legislation which can prevent this kind of abuse from taking place. But given the catalogue of abuse cases we have seen across Scotland and the UK over recent years, it is clear that we can't stand back and do nothing.

"We need a calm and considered look at child protection to see how resources can be best used to stop another young life being tragically taken in the same way as Liam Fee."

Karen Reid, chief executive of the Care Inspectorate, said: "This was a tragic and disturbing case and we note today's verdict from the court.

"All agencies who were involved with Liam must now establish if there was any action which might have been taken that could have led to a different outcome for him. If there are lessons to be learned, they must be directed at preventing future tragedy.

"The Care Inspectorate expects all services to work closely together to protect vulnerable children.

"It is everybody's responsibility to make sure children are safe, and we expect all professionals across Scotland to work closely together to ensure that appropriate information is shared; and, that rigorous assessments and care planning are undertaken to make sure that children are protected and safe."