Update at 9:40 a.m.: From Deutsche Welle:

The website of the Spiegel news magazine said the individual was named Ahmad A., who had arrived in Germany seeking asylum and had contact with the Islamist scene, as well as a history of drug use and mental health problems.

From The Local - Germany:

Officials said Ahmad A.had not filed an appeal against Germany's decision to reject his asylum application. In fact, he had helped to obtain documents to facilitate his departure from Germany. On the day of the attack, he had even gone to the authorities to ask if the identify papers had arrived. Police chief Ralf Meyer said the suspect was "almost exemplary" in this aspect.

Heavily armed police who searched a Hamburg asylum seekers' shelter where the man lived did not find any weapons.

At the asylum shelter in a leafy suburb, the suspect's neighbour, who gave his name only as Mohamed, described him as "very intelligent".

"He was always helping other asylum seekers with their paperwork," the 31-year-old Syrian refugee told AFP.

But in recent weeks, he "had a crisis, he bought Islamist clothes and read the Koran very loudly in his room".

"And three weeks after Ramadan, he had another crisis. He started to drink heavily and smoke joints... he was sad that his mother was ill and that his asylum request was rejected," recounted Mohamed.

Beatrix von Storch of the Islamophobic populist party Alternative for Germany (AfD) had stronger words, writing on Twitter that "before Mrs Merkel tweets again that this is 'beyond comprehension': this has something to do with Islam. Comprehend that once and for all!"

AfD's support has fallen back in polling since the height of the migrant crisis, but the party remains on course to clear the threshold of five percent of the vote to enter parliament for the first time [in September elections].

And the Independent is damning:

Hamburg's state interior minister, Andy Grote, said the man was a rejected Palestinian asylum seeker born in the United Arab Emirates. He said the unnamed attacker was known to have been radicalised but had not been considered dangerous and his motive remained unclear.

Torsten Voss, head of the Hamburg branch of the domestic intelligence agency, said officials interviewed the man and came away with the impression that he was a “destabilised personality” but not someone who posed an immediate threat.

Ralf Martin Meyer, the chief of the city’s police force, said that while initial findings showed the attacker had acted alone it could not be completely ruled out that he had accomplices.

Golly. More people to arrest and not deport.

Kathrin Hennings, from the state police office, said the perpetrator bought bread from the supermarket before leaving and boarding a bus, but quickly returned, took a knife from a shelf, unwrapped it and launched the attack without warning.

Officials said the man travelled to Germany from Norway

How long did he live in Norway, and in what capacity?

and initially lived in Dortmund in 2015, before being relocated to Hamburg.​ Dortmund is one of several known centres of jihadi networks in Germany and was the home of Boban Simeonovic, a leading figure in an Isis-linked group found to be radicalising young men and sending them to fight in Syria.

Anis Amri, the Isis supporter who killed 12 people at a Berlin Christmas market, spent time in Dortmund and was mentored by Simeonovic before his arrest in November. Amri attended classes at Simeonovic’s “Madrasa Dortmund”, which taught radical ideology and trained jihadis for combat in Syria.

A police informant within the network told officials the would-be attacker wanted to do “something here” in November 2015 – eight months after the Hamburg attacker arrived in Dortmund.

Simeonovic is one of five alleged members of the network currently in custody for terror offences carried out as part of a network headed by a Iraqi preacher known as Abu Walaa, who was classified as a “representative of the Islamic State in Germany” and travelled to mosques across the country.

The Hamburg attacker's suspected radicalisation was first reported to authorities in August 2016, by a friend who was concerned about a sudden change to his personality that saw him stop drinking and start talking about the Quran, while deportation was delayed by a lack of identification papers.