What rumour has followed Jim Morrison's grave ever since his death in 1971?

The answer

Dying in Paris at twenty-seven, with no autopsy and a death certificate signed by a doctor who later proved hard to trace, Jim Morrison provided legend with everything it needed. The rumour of a staged death, faked to allow him to disappear, has circulated for half a century — the grave itself, meanwhile, has never been reopened.

This question belongs to the “The Strange and the Paranormal” series of the Père-Lachaise quiz: ten questions, a story behind every right answer.