Developments so far:
- On Monday a man took over a large truck and drove it into a Christmas market in west Berlin, killing eleven people. The Polish truck driver was also shot dead in the attack.
- On Tuesday police released a Pakistani man who was detained shortly after the attack, admitting they had arrested the wrong man.
- On Wednesday newspapers reported that the ID of a Tunisian man was found in the truck's cabin. In the evening police confirmed they were hunting 24-year-old Tunisian Anis Amri. They warn that he could be armed and dangerous.
- Amri's fingerprints have been found on he cabin door of the attack vehicle. The interior minister says there is a "high probability" that he was the attacker.
- Police have been accused of a failure of duty, after various revelations about their surveillance of Amri, including that he was heard offering his services as a suicide bomber months before the attack.
5.04pm German Chancellor Angela Merkel said Thursday she was proud of the calm public response to the deadly attack against a Berlin Christmas market that killed 12 people.
"In the past few days I have been very proud of how calmly most people reacted to the situation," she said about Monday's attack.
"I am certain we will meet this test we are facing."
4.55pm The fingerprints of Tunisian suspect Anis Amri have been found inside the cabin of the truck that ploughed through a Berlin Christmas market, Germany's interior minister said Thursday.
Thomas de Maiziere said evidence indicated "a high probability that the suspect is the perpetrator" of Monday's deadly attack, adding that Amri's "fingerprints were found in the truck cabin".
3.58pm The deputy head of the Alternative for Germany, Alexander Gauland, has said that Merkel should not be blamed for the deaths on Monday.
Politicians in his party had caused outrage by describing the victims as "Merkel's dead" only hours after the attack.
Gauland said that he blamed the government's refugee policy for the attack, but not one politician directly.
3.52pm A shopping centre in the Prenzlauerberg neighbourhood of Berlin has been evacuated, due to the discovery of a suspicious object.
Trams on the Schönhauseralle have stopped and the Arkaden shopping mall has been closed down, Tagesspiegel reports.
3.47pm Police have told Spiegel why they only found Amri's ID papers in the truck on Tuesday afternoon.
The truck was first taken to a police hall so that sniffer dogs could pick up the scent of the fugitive, investigators say. If police had already entered the vehicle the scent would have become contaminated.
2.43pm Armin Laschet, the deputy leader of Merkel's CDU has said that revelations about the workings of the security services "can only have unsettled" him.
He said that their needs to be further enquiry into the failings, but added that "like so often the source is North Rhine-Westphalia."
On Wednesday North Rhine-Westphalia's (NRW) interior minister Ralph Jäger admitted that there had been a previous investigation into the suspect over a terror plot.
Laschet claimed that when Amri moved to Berlin (probably in February 216) authorities in NRW decided "it's Berlin's problem now."
It is a stinging criticism of Germany's largest state from Laschet. But it is not the first time this year NRW has been accused of police failings.
After hundreds of sexual assaults were reported in Cologne (NRW's biggest city) at New Year, authorities there were accused of covering up the crimes. The police chief was forced to resign and it was later revealed that they lied about the number of officers they had on duty.
2.00pm Pediga founder Lutz Bachmann has responded to the furore over a tweet he wrote on Monday, saying that he had "looked into his crystal ball and didn't have an informant."
Liebe Presse, ich gebe es zu, ich hatte natürlich nur meine Glaskugel und keinen Informanten!— Lutz Bachmann (@lutzbofficial) December 22, 2016
Und jetzt bitte Ruhe geben, ok?
Berlin police have also ruled out "with 100 percent certainty" that Bachmann could have an informant, saying even they did not know that on Monday night even they would be chasing a Tunisian suspect.
Amri's ID papers were found in the cabin of the truck, but when this happened is unclear.
So either police and Bachmann are covering up a highly worrying leak, or he lied - which from the man who loves to use the word Lügenpresse (lying press) about mainstream media would be ironic, but wholly unsurprising.
1.39pm Italy on Thursday confirmed that one of its nationals, a young woman called Fabrizia Di Lorenzo, died in the truck attack on a Berlin Christmas market.
In a statement the foreign ministry said German authorities had carried out the necessary checks "and now it is certain that Italian national Fabrizia Di Lorenzo was among the victims" of Monday's attack.
Di Lorenzo, 31, was from the rural Abruzzo region east of Rome. She lived in Berlin, where she worked for a haulage transport company, having previously spent time there as a student under the Erasmus exchange programme.
According to media reports, citing her family, she had gone to the market to buy Christmas presents and had been due to fly home this week for the festive break.
Di Lorenzo was the second non-German national to be confirmed dead in the attack following Wednesday's identification of Dalia Elyakim, a 60-year-old Israeli woman.
12.42pm Another headline-grabbing report on police surveillance of Amri. Spiegel reports that he had offered himself as a suicide bomber to radical preachers who were being monitored by the police months ago. But his messages were encoded in such a way that they weren't sufficient for an arrest.
12.11pm Süddeutsche Zeitung is reporting that police have found suspect Anis Amri's fingerprints on the driver door of the truck that ploughed into a Christmas market in Berlin. His ID was already found under the driver's seat.
11.54am Federal prosecutors have denied to DPA that they have made any arrests in connection with the truck attack. Bild reported earlier on Thursday that prosecutors had confirmed that arrests in Dortmund were contact men for the suspect, Anis Amri.
11.35am The Berlin Christmas market that was struck by a deadly truck rampage three days ago reopened Thursday at 11am, organisers said.
The wooden huts selling mulled wine, sausages, toys and seasonal decorations opened, though the section where the truck cut a bloody swathe through the market on Monday has been kept bare.
The Berlin association of market vendors said the decision to reopen the market was not an easy one.
"We are still stunned and deeply shocked. Our thoughts are with the injured, the dead and their families," the association's chairman Michael Roden said.
"In a situation like this it's very difficult to know what the right thing to do is."
Out of respect for the victims, Roden said the market on Berlin's central Breitscheidplatz would refrain from playing party music and keep garish lights turned off.
Two memorial sites are planned where visitors can pay their respects, the association added.
Christmas markets are a much-cherished annual tradition in Germany.
In the wake of the attack, the authorities urged organisers across the country to keep their markets open, while beefing up security.
11.06am The New York Times reported, citing US officials, that Amri had done online research on how to make explosive devices and had communicated with Isis at least once, via Telegram Messenger. He was also on a US no-fly list.
10.35am Police arrest four men in the western city of Dortmund linked to Amri, federal prosecutors have confirmed to Bild.
A prominent Salafist Boban S. lives in the city and Amri is reported to have previously lived with him. Whether he is one of the detainees is not yet clear.
10.30am The AfD and other right wing groups held a silent vigil outside Merkel's office in Berlin on Wednesday night to protest her refugee policies.
They played Bach and around 250 people truned up, including the party's deputy leader Alexander Gauland.
10.22am Pegida leader Lutz Bachmann published a strange tweet on Monday night, that could suggest the far-right firebrand has worrying connections in the police.
Just two hours after the attack he claimed "internal info from the police leadership: The attacker is a Tunisian Muslim."
Interne Info aus Berliner Polizeiführung:— Lutz Bachmann (@lutzbofficial) December 19, 2016
Täter tunesischer Moslem.
Das der Generalbundesanwalt übernimmt, spricht für die Echtheit.
His tweet was released two days before the interior ministry confirmed that it was hunting a Tunisian suspect.
Is this proof that the man convicted of hate speech for calling refugees filth has friends high up in the police or did he just get luck?
10.08am On Thursday morning around 100 police officers were involved in a raid on a refugee home in Emmerich, North Rhine-Westphalia. Suspect Amri was registered as living in the home, accord to Die Welt.
Police have given no more information on the search.