In September 2012, a man in his twenties was found dead in Portman Avenue, a suburban street in west London.

He had suffered horrendous injuries to his head and face, but had no identity papers on him - and no one had reported him missing.

It soon became clear that the man must have fallen from a plane flying overhead on to the street below.

Rob Walker has been following the police investigation into who he was and how he arrived on Portman Avenue.

It is a story that spans two continents and eight countries.

Video journalist: Andy Brownstone

You can hear more about this story on the BBC World Service Assignment programme on Thursday 13 June .