German Chancellor Angela Merkel ordered a comprehensive review of the country's security infrastructure on Friday. Her government and the Berlin police have faced hefty criticism after a terrorist killed 12 people and injured 49 at a Christmas market in the capital and managed to escape on foot.

24-year-old Anis Amri, a Tunisian national, was killed four days after Monday's attack in a shootout with Italian police in Milan. German authorities have come under increasingly intense fire from the public after it emerged that Amri was well-known to security services for his involvement with radical jihadis and was even under surveillance for six months.

Watch video 04:21 How could Amri slip through the net? Michael Böhl, president of the Berlin branch of the Association of German Criminal Investigators, speaks to DW

"The Amri case raises questions - questions that are not only tied to this crime but also to the time before, since he came to Germany in July 2015," said Merkel, referring to his prior conviction for arson in Italy, for which he served a four-year prison sentence.

"We will now intensively examine to what extent official procedures need to be changed," the chancellor added, saying she had already been on the phone with Tunisian President Beji Caid Essebsi to discuss expediting the process of deporting rejected asylum seekers. Amri's application for asylum had been turned down in June, but because it took so long to confirm his Tunisian citizenship, he was able to remain in Germany.

Amri killed by Italian police

After a massive manhunt and a number of raids across Germany, Amri was killed in the Sesto San Giovanni suburb of Milan in the early hours of Friday after drawing a gun on police officers who asked for his identification.

More came to light about Amri's victims later on Friday when the Germany's Federal Prosecutor's Office released details about their nationalities. Of the 12 dead, six were German, while the Czech Republic, Italy, and Israel have also confirmed that at least one of their citizens had been killed. The Polish truck driver of the vehicle Amri hijacked and rammed into the Breitscheidplatz Christmas market was also found dead at the scene after apparently trying to fight off the terrorist.

Police initially apprehended the wrong suspect, a 23-year-old Pakistani.

Amri was last seen in video footage from the front of a mosque in Berlin's Moabit district on Tuesday, according to German broadcaster "rbb." He arrived in Italy by train via France, but his exact movements during this time remain unclear.

es/kms (AP, AFP, dpa, Reuters)