HARI SREENIVASAN:

Anis Amri, the man suspected of carrying out Monday's attack on a Berlin Christmas market, was well known to German authorities. He was under surveillance for six months this year and was slated for deportation. But his home country of Tunisia refused to accept him.

Joining me now for more on how Amri allegedly was allowed to pull off this attack is Peter Neumann, founder and director of the International Center for the Study of Radicalization and Political Violence. He joins us tonight from Munich.

What's the latest in the investigation?

PETER NEUMANN, International Center for the Study of Radicalization: Well, the latest is that they are still trying to track down where exactly he is right now, and they are conducting raids on different places that are connected to the jihadist scene. It is now known that he was part of a wider network of jihadists in Germany, and they are raiding different places that they seem to be believing that they are connected to the scene.