"The deceased suspect Anis Amri had saved the number of this 40-year-old Tunisian national in his phone".
Frauke Koehler, spokesperson for the federal prosecutor's office, said "further investigations revealed that the detained man was not a contact person of Anis Amri's, therefore he had to be released".
Amri, a 24-year-old asylum seeker from Tunisia, was killed on December 23 in a shootout at Sesto San Giovanni district in Milan after he was stopped by police.
Before ploughing a truck into the Christmas market killing 12 people, the 24-year-old Anis Amri had reportedly sent a selfie and a chilling text message reading: "My brother, all is well, according to God's will".
Amri, a failed asylum seeker also from Tunisia, was shot dead in Italy on December 23.
ISIS claimed responsibility for the attack and released a video showing Amri pledging allegiance to its leader, Abu Bakr al-Baghdadi. Koehler said that a provisional autopsy report shows that he died close to the time of the attack, but it isn't yet possible to give an exact time.
Investigators also retrieved a.22 caliber bullet from the cab of the truck.
Surveillance cameras filmed Amri at the station last Thursday.
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They also may place a single 5-foot or smaller tree or section of a tree next to their cart for no additional charge. Trees may be dropped off in the gravel lot across from the playground and will be accepted until February 3rd, 2017.
Italian investigators are trying to determine whether Amri was tapping a jihadi network in Italy, his port of entry to Europe in early 2011 amid the Arab Spring upheaval.
That night Amri heads by bus from Nijmegen, a Dutch city near the German border, to Lyon, France.
From there, he took a train to the French Alpine town of Chambery before heading to Milan, in northern Italy.
The Sueddeutsche daily said the truck's automatic brakes had brought the vehicle to a standstill after about 80 m, preventing even more deaths.
Meanwhile Dutch lawmakers including anti-Islam politician Geert Wilders demanded an explanation over reports that Amri may have travelled through the Netherlands.
Searches by Italian authorities have focused on Rome and nearby Acilia, where he is thought to have stayed after leaving a detention centre in Sicily in 2015.
Italian Prime Minister Paolo Gentiloni told a news conference there was no evidence that Amri had any "particular networks" in Italy.