The family court judge who handed Ellie Butler back to her father who later murdered her in a fit of rage will not be officially investigated.

The Judicial Conduct Investigations Office said it would not probe Dame Mary Hogg's decision to award Ben Butler custody of his daughter after his conviction for causing grievous bodily harm by shaking her was overturned on appeal.

Butler, 36, was jailed for life last month for killing six-year-old Ellie at their home in Westover Close, Belmont, in October 2013. Both he and the child's mother, Jennie Gray, 36, were also found guilty of child cruelty.

RELATED: 'Evil' Sutton dad Ben Butler jailed for minimum of 23 years for murder of daughter Ellie

Following their convictions, Sutton Safeguarding Children Board published the findings of its serious case review, which concluded Dame Hogg's 2012 family court ruling left authorities powerless to intervene in Ellie's toxic home life or prevent her death.

Ellie was placed in the care of her maternal grandparents after Butler was found guilty of violently shaking when she was seven weeks old.

He was jailed for 18 months for causing grievous bodily harm but the conviction was overturned in 2010 after the Court of Appeal ruled the cause of her injuries could not be conclusively established.

Less than a year after returning to the care of her parents, Ellie was dead. Butler's murder trial heard the "catastrophic injuries" that killed her could only have been caused by blunt force trauma.

Ellie was returned to her parents despite Sutton Council social services pleading for her not to be.

Dame Hogg even ordered the council to send letters to education, child protection and health bodies stressing Butler’s innocence, and appointed private social workers to work with the family.

RELATED: Judge who let Ellie Butler return to dad who killed was told: 'You will have blood on your hands'

But the Judicial Conduct Investigations Office said there was no prospect of it probing the judge's decision to return Ellie to her parents.

A spokesman said: “The JCIO has no remit to investigate complaints that relate to judicial decisions or case management.

“Decisions can be appealed through the Court, where the right to appeal exists.”

Dame Hogg, 69, retired six days before Butler's murder trial began.

She has refused to accept or deny responsibility for the six-year-old’s death, telling the Daily Mirror: “It’s not personal.”

Ellie's maternal grandfather Neal Gray, who had cared for her since she was a baby, strongly protested against the move to award custody to her parents in the family division of the High Court.

He warned Dame Hogg: "You are going to have blood on your hands."

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Ellie was murdered by her own father and her mother help cover up the killing

Butler was jailed for a minimum of 22 years last month.

Gray, who helped cover up the murder, was jailed for 42 months for child cruelty and perverting the court of justice.

Speaking on the day the pair were sentenced at the Old Bailey, Christine Davies, chairwoman of the Sutton Safeguarding Children Board, sai Dame Hogg's ruling had tied authorites' hands.

She said: "The serious case review concluded that the Family Court's decision to exonerate Ben Butler of harming Ellie in 2007, combined with its subsequent order for agencies to be sent a letter to that effect, had a very significant impact on how agencies could protect his children from that point in time onwards.

"Ben Butler's exoneration and the judge's statement about him being a victim of a miscarriage of justice had the effect of handing all the power to the parents.

"This coupled with the assessment made by Services for Children to support Ellie and her sibling to be cared for by their parents were critical factors."