Investigators believe a Russian couple knocked their victims out with sedatives, then skinned them alive. Afterwards, police say, they ate parts of their victims, froze the remains or packed them in jars filled with saline solution.

At times, the couple tried to turn soldiers at the military academy where they worked into unwitting cannibals, slipping "canned human meat" into their food.

And the people in the city of Krasnodar may never have known about any of that if not for a mobile phone lying on a city street, authorities say.

City police have arrested the couple - Natalia Baksheeva, 42, and her husband, Dmitry Baksheev, 35 - who authorities say may be responsible for the death or disappearance of as many as 30 people in the city in the south-western tip of Russia.