It is a macabre challenge to detectives: Establish the identity of a murder victim whose body parts have been found in several different locations in the English countryside north of London.

A police task force is trying to analyze evidence based on a series of unpleasant discoveries, all linked, they maintain, to a single killing.

Police said Tuesday the man died of a stab wound to the back. But that information does not bring them closer to a positive identification.

"Quite lengthy steps have been taken to prevent us identifying who the victim is," said Detective Chief Inspector Michael Hanlon. "It is certainly one of the most horrific cases I have dealt with."

The gruesome case began to unfold March 22 when a left leg was found along a country road near the town of Cottered in Hertfordshire. A week later, a left forearm was found in another part of that county, north of London.

Two days later, a farmer found the man's partially decomposed severed head in a field in Leicestershire, further to the north. Then the right leg was found April 7 near a road in another part of Hertfordshire — with the torso located a few days later.

Only the hands are missing.

Police think the body parts were all dropped the same day, shortly after the actual killing.

The frightening finds, made by members of the public, were enough to make Britons think twice walking in the woods, much as Americans were afraid of taking a quick dip in the sea after the movie "Jaws" was released.

More than 100 police are working on the case, dubbed Operation Athena, and they have managed to obtain a complete DNA profile of the dead man.

But an exhaustive check of Britain's massive DNA database failed to turn up a match.

Now police are moving on to Plan B: Charging experts with reconstructing the dead man's face in a clay model with hopes that they will end up with a likeness that allows the public to identify him. The model is expected to be ready later this week.

"I need the assistance of the public to help us identify who the victim is," Hanlon said. "Once I have that identity, that opens up a large number of lines to identify who the perpetrators are."

Police have been able to determine a certain amount of information about the mystery man that may make identification easier once they have more leads.

They believe he was a stout white or Asian man of average height who suffered from several health problems, including a common fungal infection that leaves toenails discolored.

He also had a condition that lightened the skin near one of his ankles and had eczema.

Police also say two of his front teeth had been missing for a lengthy period before his death. The victim is thought to have been in his mid-40s to early 60s, police said.

The case is being handled by a task force of police from major crime units from several different jurisdictions where body parts were found.