The administrator of the cemetery in Stahnsdorf in Potsdam, Olaf Ihlefeldt, said that graverobbers had accessed the family vault of Friedrich Wilhelm Murnau, who directed the 1922 vampire movie "Nosferatu." The theft was first noticed on Monday. He added that it was difficult to pin down when exactly it had been stolen but the incident likely took place between July 4 and 12.

'Nosferatu' is considered among the highlights of Murnau's career as a director

Police have opened an investigation and called for witnesses who may have seen anything suspicious at the cemetery over recent weeks to come forward. The criminal investigation department was called in to secure evidence.

Motivation behind crime unclear

It wasn't immediately clear whether Murnau's grave was targeted specifically.

However, German daily "Bild" reported that leftover candlewax was discovered by the grave, speculating that an occult ritual might therefore have taken place. Murnau is interred alongside his two brothers; their graves were reportedly also opened during the incident but their remains were not interfered with.

Following a previous unauthorized entry to the gravesite, the cemetery said it was considering various ways to limit access to the Murnau family plot in the future. A reburial of Murnau's remains at a different site was also among those options.

Murnau's silent film "Nosferatu" is widely considered a horror classic. He died in a road accident in Santa Barbara, California, in 1931.

ss/msh (AP, dpa, epd)