A 49-year-old woman from Carmarthenshire has been arrested and bailed on suspicion of preventing the burial of a body without lawful exercise.
Jackie Powell, from Llangennech near Llanelli, is an advocate for the infamous 'Moors murderer' Ian Brady.
Her arrest follows a statement by police who say they are investigating the possibility that Brady might have revealed details about where one of his victims, 12-year-old Keith Bennett, is buried.
Brady, now 74, and his partner Myra Hindley, who died in jail in 2002, were responsible for the murders of five youngsters, including Keith, in the 1960s.
Keith was snatched by the pair on June 16, 1964 after he left home to visit his grandmother. His body is the only one that has never been found.
A Greater Manchester Police spokesperson said the force had 'received information that led officers to believe' Brady had given details of the location of Keith's body to one of his long-term visitors.
But Martin Bottomley, head of investigative review of Greater Manchester Police's major and cold case crime unit, stressed that Brady has not revealed the location of Keith's body to police.
A spokesperson for Dyfed Powys Police said the force is 'co-operating' with Greater Manchester Police following the arrest of a 49-year-old woman in South Wales.
While Brady has revealed where some of his victims were buried, he has always refused to disclose any details about the location of Keith's body.
The campaign to find the boy's body has been a long-running one. Numerous attempts to locate Keith's remains have been made in the past by the police, army and even using a US spy satellite, to no avail.
His refusal has caused constant heartache for Keith's mother, Winnie Johnson, who has cancer and has made numerous pleas for Brady to break his silence before she dies.
Brady was due to appear before a mental health tribunal in July, but it was delayed after he suffered a seizure.
The tribunal was to consider his application to be transferred to a Scottish prison and be allowed to die. He has been tube-fed since refusing food 12 years ago.
Brady has been detained at Ashworth Hospital in Merseyside for the last 25 years.
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