A white deer in the Forest of Dean was knocked down by a motorist, before having his head cut off.
The deer was decapitated, pic by Nick Davis
The fallow deer buck's body was then dumped on a railway line, according to the Forestry Commission.
A spokeswoman for the commission said it was a sad end for the animal and that it was possible the head had been taken as a trophy.
"Whether it will be sold on is another matter. It was a very messy and amateur job," she added.
The commission was alerted by a member of the public to the fatal accident, but the body had been moved by the time its rangers arrived.
It was found a day later, decapitated.
"The accident is frustrating for local people as it is such a regular occurrence and people are still not slowing down," the commission's spokeswoman added.
Two roads in the ancient Gloucestershire forest - the A4136 and the B4226 - have among the highest number of collisions between deer and cars in England each year.
Nick Davis, who took one of the only known pictures of the elusive creature, said: "There had been talk about it in the forest.
"No-one had taken any pictures so I ran off about five frames before it ran off.
"The rest is history - it was one of the few pictures taken of the famous white deer."
The police have been notified.