In Tunisia, police have arrested the nephew of Anis Amri -- the prime suspect in the Berlin Christmas-market attack, who was shot dead by police in Milan on Friday. 

Two other men have also been taken into custody. Tunisian authorities suspect the three men are members of a terrorist cell connected to Amri.

The nephew has reportedly revealed that Amri was the leader of a terrorist group based in Germany. Before the attack, he allegedly sent his nephew money and encouraged him to join the Islamic State.