Flamingo killer strikes German zoo

Fifteen flamingos have been decapitated at a German zoo in a case that has baffled police.

Keepers at Frankfurt Zoo found nine of the birds dead in their enclosure on Friday morning, and another six dead on Saturday.

Some of the Chilean flamingos were beheaded or almost beheaded as they slept, reports the Associated Press.

Frankfurt Zoo director Manfred Niekisch said staff were shocked by the incident, according to The Local.

The motivation behind the birds' death remains a mystery.

While Frankfurter Allgemeine Zeitung reported that police had found stab wounds on the flamingos, Niekisch would not rule out the deaths being caused by foxes or other predators that had broken into the enclosure.

Die Welt speculated that "psychopaths" or "Satanists" may be responsible.

Autopsies are being conducted on the birds, which were each worth around $1500, to determine how they died.

Extra security guards were posted to the birds' enclosure after the first round of deaths, but were unable to prevent more deaths because flamingos do not cry out when they're attacked, said Niekisch.

A similar incident occurred at the zoo in October 2007. The culprits were never identified.