German police are now looking for a Tunisian man as the hunt for the Berlin truck attacker continues, according to reports.
Authorities are now preparing "imminent measures" in the eastern state of North Rhine-Westphalia, according to security sources cited by German news agency DPA.
It had previously been reported by Der Spiegel that a man known as Anis A. has become the main suspect after police found an ID under the seat of the truck which was driven into a packed Christmas market on Monday.
It is also reported that Anis A. was born in Tataouine in 1992.
The Allgemeine Zeitung newspaper reports that the suspect is known by several other aliases, including Ahmed A., and states that his documents were issued in the district of Kleve in North Rhine-Westphalia.
Police had earlier detained a 23-year-old Pakistani man, but he was released without charge after investigators said they didn't have enough evidence to bring charges.
Islamic State has claimed responsibility for the attack, but their role in the atrocity has yet to be verified by official sources.
At least 12 people were killed in the attack while dozens more injured. German Chancellor Angela Merkel has come in for widespread criticism of her open-door immigration policy in the wake of the incident.