Adam's body was found without a head

Officers say Kingsley Ojo, 35, was part of a network that may have brought the youngster into Britain.

The connection came out during his trial at Southwark Crown Court on Tuesday, when he pleaded guilty to identity and trafficking offences.

The mutilated body - dubbed Adam by police - was found in September 2001.

Detective Chief Inspector Will O'Reilly said the defendant was detained during a series of co-ordinated raids "because of his association with an earlier arrest in this case.

Forensic teams linked the boy back to Benin in Nigeria

"We have always had suspicions that he is part of a trafficking network that may have brought the young child into the country.

"We now know he came from the same area of Nigeria as the child and other people arrested in connection with the murder inquiry, and that is Benin City."

Ground-breaking forensic work, which involved taking samples from the child's bones, first linked him to West Africa and then to Nigeria - the hunt led to a rural area measuring just 50 X 100 miles in the south-west of the country.

A mixture containing quartz, bone, clay pellets and small samples of rough gold, led police to suspect he had been the victim of a so-called "muti" ritual killing, possibly by witch doctors.

Mr O'Reilly, who said a "full case file" had been submitted to the Crown Prosecution Service concerning the youngster's killing and was "awaiting their decision", made it clear he was now interested to see if Ojo could directly assist in the investigation.

Ojo, of Stratford, east London, pleaded guilty to four charges.