He was released in May 2015. Police had arrested 23-year-old Pakistani national Naved B. near the scene of the crash but he had denied any role in the attack.
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The German interior minister, Karl-Heinz Schröter, confirmed the driver was a victim and not an assailant in the market attack.
German federal prosecutors say they are in contact with Italian authorities.
"We have in the meantime no doubt anymore that this terrible event last night was an attack", de Maiziere told reporters in Berlin.
"A unit of the anti-terrorism brigade has questioned the suspect's family", the official said, speaking on condition of anonymity. They said it remains unclear if the perpetrator was acting on his own or with others, Reuters reported.
Italian media reported that a 20-30 year old man of Middle Eastern appearance opened fire on police officers during a security check.
Germany had launched a Europe-wide manhunt for Amri, who was described as "violent and armed". But you can move around safely in public places.
Urban's boss, Ariel Zurawski, told Bild that his employee was unable to unload his freight as planned because he arrived just a few minutes after schedule.
Police continue to hunt for the person behind the attack, with the main suspect urged to surrender by his family.
The subsequent order of events was not immediately clear, but the attacker is believed to have hijacked the truck at some point in the late afternoon before carrying out the 8 p.m. attack, which the Islamic State claimed responsibility for on Tuesday. The statement is hard to verify as there is now no suspect in the case but the group rarely issues a claim of responsibility while the main perpetrator is still alive.
He left for Germany more than a year ago, according to his father.
Merkel's open-door refugee policy of previous year polarized voters and fed support for the anti-immigration Alternative for Germany party, known as the AfD.
In a nationally televised statement in Berlin, Merkel said that people across Germany were mourning after the "horrific and unimaginable" deaths and injuries sustained in the capital on Monday evening.