The murder of vulnerable Hartlepool woman Angela Wrightson by two teenage girls could not have been prevented, official reviews have found.
Two Serious Case Reviews and a Safeguarding Adults Review were carried out after the murder of Angela at her home in Stephen Street in December 2014.
The girls, aged 13 and 14 at the time, who cannot be identified, were sentenced to 15 years custody in April of last year.
The review of the case also found that the girls were already known to social services for running away, drinking and being sexually active.
They attacked 39-year-old Angela with a shovel, a TV, a coffee table and a stick studded with screws. They subjected her to a five-hour ordeal.
Hartlepool Local Safeguarding Children Board and the Teeswide Safeguarding Adults Board carried out reviews into what happened.
Reports concluded the murder could not have been prevented and that all parties, including Angela, had received a high level of intervention from social services.
The older girl, referred in reports by the pseudonym Olivia, had a chaotic home life and was placed into care.
Aged 12, she told care professionals her father had, wrongly, told her her mother was dead.
As far back as August 2012, while she was living with her mother, a social worker found the parent in a distressed state, claiming "[She] was drinking, going to parties, possibly having sexual intercourse and hitting" younger siblings.
Two months before the murder, when the older killer was living in a care home, she was arrested for assaulting three members of staff and causing damage to the premises.
The younger girl, named Yasmine in the reports, had been put in foster care after her parents complained of being unable to cope.
The report stated there were concerns about her bullying at school, and aggression towards her parents.
It said: "She was known to drink alcohol and use drugs, and there were escalating concerns regarding possible underage sexual activity.
"Services and support were provided, but neither the parents nor [the girl] engaged and the circumstances deteriorated."
The reports into both teenagers found parents were quick to criticise their daughters' behaviour, but unwilling to accept help to address it and to improve their parenting.
Dave Pickard, chair of Hartlepool LSCB, said: "Neither young person had a criminal history and no history of any significant assaults on any other individuals.
"Their behaviour was troublesome and anti-social before the night in question, but there was no suggestion whatsoever of any serious violence: it was a total shock to everyone."
A selfie posted to Snapchat during Angela's ordeal showed the defendants smiling, while she was pictured in the background shortly before her death, with further selfies showing the girls drinking cider from a bottle.
After the attack, the girls rang the police to take them home and they took a photo, also posted to Snapchat.
Ann Baxter, chairwoman of the Teeswide Safeguarding Adults Board (TSAB), said: "This really was a sad and shocking case, and everyone who was involved in [Angela's] life, in particular her family and the staff who worked directly with her, were left devastated by what happened.
"The Safeguarding Adults Review is very clear and the independent author has concluded that this could not have been predicted and therefore could not have been prevented."
But officials say all the organisations that were involved with Angela and her killers could have shared more information and been more coordinated, and are looking at how they can share information better.
Mr Packard added: "The reports provide the board with a number of findings and all board members accept these and are fully committed to ensuring everything is done to minimise the risk of a similar tragic event ever happening again."
All the partner organisations say they are working together to develop action plans to address the reviews' findings which will be monitored by the Hartlepool Local Safeguarding Children Board and Teeswide Safeguarding Adults Board.