Nelson Mandela yesterday appealed to fellow Africans to help British detectives investigate the killing of a boy whose torso was found floating in the river Thames last year.
Police believe the boy, whom they call Adam, might have been the victim of a ritual "muti" killing, the first of its kind in Britain.
The former South African president said the case had left him with sadness and a deep sense of tragedy.
"It seems likely that the boy might have come from Africa ... I wish to direct my appeal specifically to people in Africa.
"If anywhere, even in the remotest village of our continent, there is a family missing a son of that age, who might have disappeared around that time, September 21 2001, please contact the police in London, either directly or through your local police."
Mr Mandela praised the "sterling contribution" of South African detectives and pathologists to the case.
He added: "Such cruel wastage of the lives of our children and youth cannot be allowed to continue."
Police suspect the boy was from Africa after forensic experts analysed the contents of his stomach and found traces of pollen and food not normally found in the northern hemisphere.
Two Scotland Yard detectives, Commander Andy Baker and Detective Inspector Will O'Reilly, have been touring muti markets and meeting South Africa's leading traditional healers and academics in search of some insight into the boy's murder.
"This type of crime is entirely beyond our experience," Mr O'Reilly said during their week long visit to Pretoria and Johannesburg.
"We have come here not because we think Adam came from South Africa, but because this is where the experts are who can help us understand this culture and belief system."
A postmortem examination revealed that Adam suffered "severe trauma" to the neck. His limbs and head were removed after death.
Credo Mutwa, one of South Africa's leading sangomas, or traditional healers, was one of the first spiritual leaders the men visited.
At his home 20 miles outside Johannesburg, which was filled with candles, medicinal plants and small statues, he suggested a link with a west African form of witchcraft involving "the horriblest form of human sacrifice, usually on a child who has not yet reached puberty".
Police have already speculated that the boy is from that part of the continent as he was circumcised, a rite which is unusual in South Africa until the age of 18, but commonly happens with infant boys in west Africa.
Mr Mutwa said the killers would have drunk the boy's blood after death, using a "skullcap" cut from the severed head.
His finger joints would have been used as charms or ground into paste as part of a ritual to give the criminals strength.
"I think this is a human sacrifice to some sort of water deity carried out by a gang of people strengthening themselves to do some very ugly crimes. They have made this sacrifice because they are filled with fear for what they have done or what they are going to do."
He said the orange shorts, which the child was dressed in after his death, "signified a resurrection" and concluded that a close member of the boy's family would have been involved in his sacrifice.
After the meeting Mr Baker said: "It was very useful to spend time with Mr Mutwa. He has given us valuable insight and has also provided us with some names of other traditional healers."