The severed heads of four men had been left on the verge, the identification documents of their owners carefully placed next to them.
They were found by an unnamed motorist, less than 50 miles from the capital city, Grozny, and it was immediately clear who they were.
Ruslan Musayev, a reporter for the Associated Press who also witnessed the ghoulish scene, said: "I saw the heads neatly lined up beside the highway. They were lined up on a piece of cloth in plain view of passers by.
"Two of the heads had wounds to the temple, possibly gunshot wounds," he said.
Chechen fighters prevented journalists from filming the scene on the deserted road between barren wintry fields nearthe village of Dovydenko.
"It appeared that somebody had brought them and dropped them by the roadside for all to see," the motorist told a correspondent for Russia's independent NTV channel.
Within an hour of the find, Umar Makhauri, who had been one of the engineers' bodyguards, came to the roadside and recognised the faces of the dead men.
He was certain that they were Peter Kennedy, Darren Hickey, Rudolf Petschi and Stanley Shaw.
Last night the victims' heads were said to have been taken to Grozny morgue.
No bodies were found by the roadside, although the Chechen leader, Aslan Maskhadov, said later that the corpses had been found elsewhere. The testimony of the unnamed driver was relayed by an NTV correspondent, Said Tsarnayev, who said that Chechen gunmen then closed the roads in the area, and people were too afraid to approach.