West Mercia Police has asked another force to carry out an investigation into the police handling of 'previous incidents' of murderer Jamie Reynolds.
Reynolds was given a whole life jail term for the murder of Georgia Williams, from Wellington in Shropshire, last year.
The Independent Police Complaints Commission recommended that the investigation should be managed by West Mercia Police, but the force has asked Devon and Cornwall Police to conduct the inquiries, saying it would be "more appropriate" for the investigation to be carried out by another force.
In a statement, West Mercia Police, said: "As an investigation is therefore still pending it would be inappropriate for us to comment further around the specific details of the enquiries at this stage."
The man who killed teenager Georgia Williams plotted the murder to give himself "sadistic pleasure", the judge said.
Mr Justice Wilkie said in sentencing: "You watched her die in circumstances where you could have saved her - and doing so was a central part of your pleasure...[You] then treated her body with contempt, dumping her in a remote area."
Continuing to address Jamie Reynolds, who stood head bowed and with his hands clasped behind his back, he said: "This is not a marginal or borderline case. I am in no doubt the seriousness of your offending, so a whole-of-life term is the starting point."
"I take very seriously the conclusion of (psychiatrist) Prof Paul Peckitt that you have the potential to become a serial killer," he added.
Stafford Crown Court has heard how a psychiatrist's report suggests Jamie Reynolds "poses a grave risk to women and will do for the rest of his life." It also says he "has the potential to be a serial killer."
The report also says there is "not one shred of clinical evidence to suggest he did not know what he did was wrong."
A judge has described, in court, the murder of Georgia Williams as being "a highly unusual and exceptional case."
23-year-old Jamie Reynolds is yet to be sentenced for her murder. The prosecution described him as "a sexual deviant of an extreme kind" with "a morbid fascination of pornography."
He had a hard drive of extreme pornography that the prosecution described as "a prized possession" and which went everywhere with him. He also wrote stories about hanging and death.
The court heard how he had written a story about Georgia where he hanged her and subjected her to sexual violence.
It was also told how he groomed the 17-year-old over a period of several months and encouraged her to come to his house when his parents were away to take part in a photo shoot, to help with his photography.
The court heard he stood and watched her die before subjecting her to sexual violence and taking photographs of her naked body.
After killing Georgia he went online to send messages to two other girls he had arranged to visit his house in case she did not arrive.
A 23-year-old man killed teenager Georgia Williams after luring her to his parents' house and hanging her, a court has heard.
Jamie Reynolds was a "a sexual deviant", "a manipulative and conning individual who operated in denial" and had "a morbid fascination" in extreme pornography depicting violence against women, prosecutor David Crigman QC said.
Reynolds pleaded guilty earlier this month to murdering 17-year-old Georgia in May, on what was scheduled to be the first day of his trial at Stafford Crown Court.
Mr Crigman said that at the time of his arrest for murder, Reynolds had 16,800 images and 72 videos of extreme pornography on his computer, including digitally-doctored images of up to eight other women he personally knew in which ropes had been added around their necks.