The boy's torso was found floating in London's River Thames. His arms, legs and head have never been recovered and police believe his body parts may used for traditional medicines.
There are no statistics for the number of muti murders in South Africa and estimates vary from one a month to 300 a year, according to Gerard Labuschagne, commander of the South African Police Service's investigative psychology unit.
Such killings are usually distinguished by the dismembered bodies of the victims. It is believed that body parts -- including internal organs -- are sometimes removed from victims still living, in the belief that their screams enhance the medicine's power.
"The removal of genitals is very characteristic," Labuschagne says. "The parts have different significances -- a hand might be used by a businessman who wants to attract customers. Genitals are a source of good luck."
In the London case, the killers removed the boy's "Atlas" bone -- the vertebra that connects the neck and spine.
"If it was a muti murder, then the bone is a symbolically important part of the body," Labuschagne said.
But there are also hundreds of muti medicines, which are widely used, containing nothing more sinister than plant extracts.
There are muti cures for headaches -- a type of light-brown snuff -- and an olive-green mixture is said to help kidney problems, or drops to ease high blood pressure.
There are herbal concoctions that can make you more sexually powerful -- different kinds for men and women.