The parents of murdered teenager Georgia Williams have attacked "disastrous" failings identified by a serious case review into previous attacks carried out by her killer.
A serious case review into police and social services' contact with murderer Jamie Reynolds criticised a "confused" inquiry into his attempt to strangle a 16-year-old girl in 2008.
Georgia's parents, Steve and Lynnette Williams, believe previous incidents involving Reynolds, who was obsessed with extreme pornography, show he was a "murderer in the making".
The serious case review said Reynolds came to the attention of police five years before the murder, when he tried to attack the 16-year-old girl in a "bizarre, potentially serious and unprovoked" manner.
Reynolds, who is a serving a whole life sentence, went on to kill 17-year-old Georgia after luring her into his home in Shropshire in 2013.
The then 23-year-old invited Georgia to his home for a photo shoot but killed her in a meticulously planned trap, hanging her from a length of rope attached to the loft hatch.
The review said Reynolds, who was known to watch violent pornography featuring women being hanged, trapped the 16-year-old at his home and grabbed her around the throat.
Police treated the incident as assault, did not take photographs of the injuries and did not search Reynolds' home.
He was given a final warning and offered counselling.
The serious case review also gave details of how Reynolds had also drawn nooses on pictures of girls he knew, including Jadine Dunning.
Ms Dunning was only shown the offending photograph after Georgia has been murdered.
Speaking to BBC's Today programme, she said: "I strongly believe, as a close member of that family will also agree with me, that if action had been taken, if they had given me some form of warning, Georgia would still be with us today.
"There is no doubt in my mind. She was a sensible young girl and all it would have took is for her to come home, say she was friends with Jamie Reynolds and (someone) could have said 'no, this, this and this has happened, you need to be wary and stay away'."
In a joint statement giving their views on the review, Mr and Mrs Williams said: "We appreciate West Mercia Police initiating this report, having recognised that the 2008 investigation was inadequate to say the least.
"However, considering that multi-agency resolutions are considered a way of achieving best results this report shows how this approach is disastrous.
"Having lost Georgia to pure evil, we cried when we read this report and the failings of all agencies involved because it was so obvious that Reynolds was, if not one already, a murderer in the making."
Georgia's father described the findings of the review as "an embarrassment" to the police, and claimed his daughter's death could have been prevented.
Mr and Mrs Williams also called on West Mercia Police to publish a further report prepared by Devon and Cornwall Police which they said highlighted mistakes "10 times worse" than those identified by the serious case review.
The independent Devon and Cornwall report, given to the West Mercia force in March, led to misconduct proceedings against four officers and one civilian staff member who face a sanction stopping short of dismissal.
Georgia's father told a press conference in Telford, Shropshire: "It (the Devon and Cornwall report) should be released because it gives all the answers to the questions that remain."
The discretionary serious case review by West Mercia's public protection management board raised "serious concerns about the quality of the investigation" in 2008, adding the police inquiry into the incident was "narrow in its perspective" and seemed "aimed at ensuring a speedy resolution".
After the attack in 2008, a doctor then assessed Reynolds as being a significant risk to others "on the basis that he seemed to have progressed from viewing sexually violent pornography to acting upon it" when he attacked the teenager.
Eight agencies were involved after the attack, but the report says there was a "confused and uncoordinated approach to the case" among the people looking after Reynolds, including mental health services, police, children's services and the probation trust.
"The work undertaken in respect of Reynolds following the offence in 2008 was disjointed, lacked focus, did not include a clear multi-agency risk management plan and was restricted to single agency, short term perspectives," the report concluded.
Three years later, Reynolds was again reported to the police for reversing his car into that of a girl who had spurned his amorous advances.
The report said: "When Reynolds came to the attention of the police in 2011 for what was clearly an offence with some links to the 2008 offence, no link was made to the information existing within police files.
"Following the murder of Georgia, the matter was investigated further and that that point it became clear that Reynolds' inappropriate behaviour in relation to his colleague had been persistent and increasingly obsessive.
"His actions at the time of the incident and immediately following it had a number of parallels with the 2008 offence.
"It is clear that had this matter been looked into in more detail it would have highlighted Reynolds' ongoing and developing behaviour and the need for serious concern about the risks he posed."
Mr Williams, a detective with West Mercia Police, said of the serious case review: "We cried when we read this.
"And we cried even more when we read the Devon and Cornwall (review) and the context of it, and the answers to why officers didn't do what they should have.
"In our eyes it's 10 times worse and it would be an embarrassment to the police, like this is an embarrassment to the police.
"But I think it should come out because it gives you the answers. This is only half the story, It's like reading a novel and closing it half way through and not knowing the end."
The report made five recommendations which relate to improving the sharing of information between agencies, as well as raising concerns nationally about the lack of guidance for staff when dealing with potentially serious offending at the point of transition from youth to adult.
It added: "It is inevitable that awareness of these shortcomings will cause distress to the parents of Georgia and it is of general concern that, for whatever reason, the investigation into the case was not as thorough as might reasonably have been expected."
Chief Constable of West Mercia Police, David Shaw, said: "We could and should have done better. It is as simple as that.
"We let Georgia down. We let Steve and Lynnette down. And as you'll see in the report - some other young people, we let them down as well.
"What that report reflects is a whole series of things that the police and other agencies can do to improve, and make sure the failings do not happen again."