Detectives have acknowledged they could have "overstepped the mark" by saying they believed allegations of a murderous VIP paedophile ring may have been true, the director of public prosecutions has said.
Alison Saunders, the head of the Crown Prosecution Service, said that investigations like Operation Midland - which is examining claims of murder and child abuse by establishment figures - were difficult, but that "you don't just take somebody's word as it is".
She spoke after Scotland Yard yesterday acknowledged that a Midland detective's description of an alleged victim's claims as "credible and true" had "suggested we were pre-empting the outcome of the investigation".
Appearing on the BBC's Victoria Derbyshire Show, Ms Saunders said: "They are now saying, quite rightly I think, that in order to launch an investigation there had to be credible evidence, they perhaps have acknowledged today that they overstepped the mark in saying it might have been true.
"It's a very difficult balance, people won't come forward - when we have talked to victims and witnesses one of the things they say they fear most is being judged and disbelieved. But it is absolutely our job and the police's job to investigate it and to decide whether there is sufficient evidence to put before a court. You don't just take somebody's word as it is."
Operation Midland was set up by Scotland Yard following historical claims that a VIP paedophile ring including MPs was linked to the murder of three children between the mid-1970s and mid-1980s.
When it was launched, Det Supt Kenny McDonald said officers who had spoken to an alleged victim known as "Nick" thought his account was "credible and true".
Last month former Tory MP Harvey Proctor, who has been questioned over the claims, insisted he is a victim of a "homosexual witch hunt" and called for "Nick" to be stripped of his anonymity.
The Metropolitan Police yesterday said: "We should always reflect that in our language and we acknowledge that describing the allegations as 'credible and true' suggested we were pre-empting the outcome of the investigation. We were not.
"We always retain an open mind as we have demonstrated by conducting a thorough investigation."
In the statement Scotland Yard also defended its investigation so far, saying the historic nature of the allegations "means this is a complex case where the normal avenues of evidence-gathering from CCTV, DNA and telephone data are not open to us".
"We must add that whilst we start from a position of believing the witness, our stance then is to investigate without fear or favour, in a thorough, professional and impartial fashion, and to go where the evidence takes us without prejudging the truth of the allegations," it added.
"That is exactly what has happened in this case."
Operation Midland includes allegations of sexual abuse but it is "and remains" a murder investigation, the statement said.