The searches were conducted in the town of Aprilia on Wednesday, La Repubblica newspaper said adding that investigators thought Amri was headed for central or southern Italy after the deadly attack and some people with links to the suspect could still reside at the locations.
On December 19, a truck drove into a crowd at a Christmas market in the center of Berlin, killing 12 people and injuring over 40 others.
The suspect, 24-year-old asylum seeker from Tunisia Anis Amri, traveled from Germany through France after the attack, heading for Italy. On December 23, Italian Interior Minister Marco Minniti announced that Anis Amri had been killed in a shootout with police in Milan early in the day.
The German Interior Ministry considers the deadly Breitscheidplatz square Christmas market attack a terrorist act.