A passer-by found the bones in two black bin bags in the River Stour, Suffolk, in 2020 - though police believe the victim died between 2008 and 2012 and are treating it as murder.

However, the man, who has yet to be identified despite his DNA profile circulating local, national and international databases, may not have died from the cuts.

Detective Superintendent Mike Brown said: "The skull fragments actually were quite small in themselves so we don't have a complete skull, but across the top of the skull in a linear format were 27 quite deep lacerations or injuries.

"Through the post-mortem process the pathologist identified those were probably caused by a heavy-bladed weapon but wouldn't necessarily have been the cause of death."

Using radiocarbon dating - a way of determining the age of an object - and other forensic means, police now believe the victim is a white man likely of northern European origin in his 50s or 60s and of athletic build.

"They were probably born with blond hair though that may have changed over time, blue-green eyes, 5ft 6ins to 5ft 9ins in height, and muscular or athletic build as a description," said Mr Brown.

The full remains discovered were part of the man's skull and jaw, the right and left arm bones and partial wrist bones, and the complete lower right and left legs, including the feet.

The remains of the arms, legs and feet were partially mummified and there was a healed fracture to one of the wrist bones.

Mr Brown said the first black bin bag contained what is believed to be the arms, the second contained legs and there were "other carrier bags with stones and bricks that have weighed down the contents".

Mr Brown said there was a smell coming from "what we initially described as air fresheners, the type of thing you would see in public toilets to potentially block any smell" from the remains.

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Police are working on three theories to establish the reason for the disposal of the remains - whether somebody doing building work threw the remains away, or if a family "who may have been claiming benefit fraud for a deceased relative and again something happened that meant they had to dispose of the remains".

Officers' remaining hypothesis is the man's death could be related to organised criminality because of the "expertise" shown in the dismemberment of the remains.