On Monday Germany suffered its first 'real' Islamist terror attack, as one analyst put it.
Finance Minister Wolfgang Schäuble said he wasn't surprised, commenting that it was a matter of when not if jihadist terror came to Germany.
But revelations about the prime suspect, Anis Amri, since the attack, which killed 12 people, are leading to serious questions about the competence of Germany's security services.
Armin Laschet, the deputy leader of Merkel's CDU, told Deutschlandfunk on Thursday that revelations about the workings of the security services “can only have unsettled” him.
He has accused investigators in western Germany of washing their hands of the prime suspect, despite knowing he was a danger.
Christian Lindner, leader of the Free Democrats went further, saying “there has clearly been a state failure here that cannot be tolerated.”
Rainer Wendt, head of the German Police Union, has firmly rebuted the accusations
“I find it shameful to talk of a failure on the part of the authorities in the case of Anis Amri – especially when it's a politician like Armin Laschet who does it,” he told the Rheinische Post.
Here are the key facts so far:
What is the evidence against the suspect?
24-year-old Anis Amri's ID papers were found in the cabin of the truck, under the driver's seat.
On Wednesday Süddeutsche Zeitung reported that his finger prints have been found on the door of the truck.
Together these pieces of evidence already appear to build a strong case against the Tunisian.
Why did they only release his name on Wednesday?
One of the main questions being asked is why it took so long to identify him as the prime suspect.
It seemed too good to be true when police said Monday night they had arrested a suspect within an hour of the attack – a Pakistani man who had apparently been identified by an eyewitness.
It took until Wednesday afternoon for authorities to issue a Europe-wide public wanted notice that gave Amri's full name, age and photograph and warned the public he was dangerous.
Police say that a suspect's 24/7 phone and personal surveillance requires a rotating team of up to two dozen officers. German security services say they are keeping an eye on some 540 radical Islamists they consider potentially dangerous.