The search for Dr Ruja Ignatova takes an unexpected turn when a story emerges alleging she's been murdered. But with with sightings of Dr Ruja still coming in long after her apparent demise, can it be true? We speak to the Bulgarian journalists behind the story and team up with BBC colleagues to investigate the murder theory. It takes us on a trail to a Bulgarian man widely suspected of heading an organised crime organisation. Meanwhile, a trusted former adviser to Dr Ruja disappears, just like his old boss.

Presenter: Jamie Bartlett