BERLIN (AP) -- German officials have a new suspect in the deadly terror attack on a Christmas market in Berlin has been identified.
Law enforcement sources told CBS News that police are searching for Anis Amri, a native of Tunisia. The sources said Amri left personal documents in the truck. German media outlets have identified the Tunisian man as an asylum seeker who was registered in the North Rhine-Westphalia in Western Germany.
This week, the Islamic State extremist group claimed responsibility for the truck attack on a Berlin Christmas market that killed 12 people and left nearly 50 injured.
The Islamic State group's Amaq news agency said in a statement Tuesday that "the person who carried out the truck run over attack in Berlin is a soldier of the Islamic State and carried out the attack in response to calls for targeting citizens of the Crusader coalition."
German police are still hunting for the driver of the truck, which slammed into the downtown Christmas market Monday night.
Germany is not involved in anti-IS combat operations. But it does have Tornado jets and a refueling plane stationed in Turkey in support of the coalition fighting militants in Syria, as well as a frigate protecting a French aircraft carrier in the Mediterranean.
German prosecutors say a man arrested after the truck attack on a Berlin Christmas market has been released because there isn't sufficient evidence to tie him to the rampage.
Federal prosecutors said Tuesday that that the man, a Pakistani citizen who came to Germany last year as an asylum-seeker, denied involvement in the attack that killed 12 people and injured nearly 50 others.
They noted that witnesses were able to follow the truck's driver from the scene but lost track of him. The man arrested matched witness descriptions of the truck driver, but investigators haven't been able to prove that he was in the truck's cab at the time of the attack.
Under German law, prosecutors have until the end of the calendar day following an arrest to seek a formal arrest warrant keeping a suspect in custody.