Anis Amri, the Tunisian responsible for the death of 12 people by driving a truck into a Christmas market in Berlin received his orders directly from the terror group ISIS, a German magazine reported on Saturday.

ISIS group claimed responsibility for the attack on Dec. 19, but it was unclear whether it had any direct involvement with planning or execution.

Some proposed that the terror organization had merely inspired the attacker with its calls on supporters to hit targets in enemy countries.

Der Spiegel cited information provided to German security authorities from the United Arab Emirates on Jan. 8 that said Amri, the failed asylum seeker who drove the truck into the crowd, had received an order from an ISIS-linked cell.

The squad is known to German authorities from other proceedings against suspected ISIS militants disguised as refugees, the magazine said.

Amri, who had pledged allegiance to ISIS, was shot dead by Italian police in Milan four days after the Berlin attack. ISIS said the attack had been perpetrated by an ISIS “soldier … in response to calls to target nationals of the coalition countries”.

The federal public prosecutor’s office and the BKA federal police are looking into the information provided by the UAE, the magazine said, adding that German authorities considered the source reliable.

When asked for comment, the BKA said the federal public prosecutor’s office was responsible for providing information on the Amri case. The prosecutor’s office refused making any comments.

On Wednesday, the prosecutor’s office said it had no evidence that other people based in Germany were involved in preparing or carrying out the attack and an evaluation of Amri’s mobile phone showed he had communicated with an ISIS member abroad before and during the attack.