The address of a girl murdered on her doorstep by her estranged father was accidentally sent to him by her mother's solicitor, it has emerged in a serious case review.
Seven-year-old Mary Shipstone was returning to the safe house from school with her mother when Yasser Alromisse shot his daughter in the head - then turned the gun on himself.
Five months earlier, the girl's mother, Lyndsey Shipstone, reported to police that her solicitor had inadvertently revealed her new address to Alromisse in legal papers, the review revealed.
Evidence or strong suspicion also emerged that details of her previous addresses or identity were given to 46-year-old Alromisse by other bodies, including a bank and the Child Support Agency.
Despite the disclosures, the serious case review concluded that no-one could have predicted or prevented the killing in Northiam, near Rye, East Sussex, on September 11 2014.
It said there was no evidence Alromisse located his daughter and estranged wife through the inadvertent disclosures of the girl's address and her mother's circumstances.
The criminal investigation into Mary's shooting found Alromisse had used "a variety of covert and illicit means" to try to trace the address and the routine of his daughter, referred to as Child P.
The 73-page serious case review report noted: "It has not been possible to establish exactly when and how he found out where Child P was living.
"There is no evidence that any professional was aware of this activity, nor did he make any threat to harm Child P or give any indication that he might do so.
"The review has concluded that no professional working with the family could have prevented him acting as he did."
Mary's death "was calculated to deprive the mother of her child while at the same time leaving her with a permanent memory of her death", the report said.
And it added that Ms Shipstone believed Alromisse killed their daughter because he feared the outcome of a new round of court hearings would end in him being denied contact.
At an inquest in September last year, East Sussex coroner Alan Craze said the "thoroughly despicable act of violence" had been "pre-meditated over a long period of time".
The inquest heard Ms Shipstone carried Mary to a neighbour's home, where they tried to revive her while waiting for emergency services to arrive. She was taken to King's College Hospital, London, but later died of her injuries.
A series of recommendations were made in the review, including seeking assurances from agencies that systems were in place surrounding information about vulnerable people that should not be revealed.
A spokesman for the East Sussex Local Safeguarding Children Board said: "After a thorough independent review, the LSCB concluded, as did the investigating police officers, that the father planned and carried out the killing in a secretive way, using the internet and a range of covert methods to trace the family and obtain the means to carry out the murder.
"There is no evidence that any professional involved with the family prior to these tragic events was aware of this activity. Based on the review, the LSCB concludes that no professional could have prevented him doing what he did.
"The LSCB has also found that professionals did respond diligently to reports of domestic violence, which were all taken seriously and responded to appropriately.
"As is always the case, the review has, however, found some areas where improvements could be made, particularly around how information is shared when families move areas, and we are working with all agencies involved to implement a small number of recommendations to improve practice."