When hero cop Luca Scata shot Europe's most wanted man, Anis Amri, it brought to an end the Berlin attacker's four-day flight which saw him travel three different cities in three different countries, reports The Sydney Morning Herald.
Alberto Nobili, coordinator of the anti-terrorism department at the District Attorney's Office in Milan says Amri ended up in the Italian city after travelling from Berlin to the French city of Chambéry and via a stop in Turin.
The drive between Berlin and Chambéry takes about 11 hours. The train ride between Chambéry to Turin takes just under three hours. Whatever method the 24-year-old took, he would not have needed to show a passport because he was travelling within the Shengen area which allows passport-free travel.
The Italians were unaware that the Tunisian was amongst them.
He had recorded a video message for Islamic State, it emerged on Friday.
Islamic State adherents are encouraged to send out such video pledges before launching attacks, The New York Times reported. Similar claims have been made by men who carried out assaults in Paris and Orlando, Florida. The videos have been recorded on laptops and cellphones and distributed through mediums like Facebook Live.
"We had no intelligence that he could be in Milan," Milan's police chief Antonio De Iesu said.
It was only that Amri was loitering near the train station near the Piazza Primo Maggio, in Sesto san Giovanni, Milan at 3am that police patrolling the area asked for his identification, suspecting he might be a burglar.
When Amri pulled out a gun, it was clear he was a far more dangerous sort of criminal, although they had no idea he was Europe's most wanted fugutive who had managed to traverse undetected three countries across the continent.
He shot at one of the policemen, lightly wounding him in the shoulder.
Amri then hid behind a nearby car but the other police officer, a trainee, managed to shoot him once or twice, killing him on the spot, police said. Amri was identified by his fingerprints. He did not have a phone on him and was carrying a small pocket knife and a few hundred euros.
On the night of the attack German police had arrested a 23-year old Pakistani migrant who denied involvement. He was later released due to a lack of evidence.
Chancellor Angela Merkel has flagged strengthening Germany's counter-terrorism laws and has told Tunisia's President that the repatriation of failed asylum seekers, like Amri, must be made easier. Amri should have been deported to his home country but could not be sent home because he did not have identity documents. He would use six different aliases.
The German Prosecutor, Peter Frank, said it was yet to be established how the culprit managed to escape their net.
"We want to investigate how he managed to get to Milan and whether he had any assistance or accomplices. We will look at what contacts he made in the preparation of the attack – people who may have supported him with money and aided him in the escape," he said.
"We need to establish whether there was a network of accomplices. That is the focal point of our investigation."