Five people, including a nine-year-old boy, were killed when a man drove a car a crowded Christmas market in Magdeburg, Germany, on December 20.
More than 200 people were injured in the attack on Friday evening, including about 40 people who were seriously or critically injured.
On Tuesday, German President Frank-Walter Steinmeier used his Christmas address to the nation to call for national unity.
He said: “There is a dark shadow over this Christmas.”
“Hate and violence should not be the last word. Let us not be distracted. Let's stand together.
Authorities said the suspect used emergency exits to get to the Christmas market, where he made his way through the crowd in a three-minute race. The man surrendered himself to the police at the scene.
The Magdeburg police department said in a statement on Sunday that the suspect has been placed under investigation on five counts of murder and several counts of attempted murder and grievous bodily harm.
Here's what we know about the suspect:
Who is being considered?
The a suspect identified as Taleb al-Abdulmohsen, a 50-year-old psychiatrist from Saudi Arabia who has lived in Germany for nearly two decades.
He works at an addiction treatment center but has been on sick leave since late October.
He has described himself as a “Saudi anti-God” and anti-Islamist who has helped ex-Muslims flee the Gulf states.
Al-Abdulmohsen has been working on the Internet, against Germany for accepting large numbers of Muslim refugees and supporting the idea of a far-reaching conspiracy about the “Islamisation” of Europe.
Der Spiegel magazine reported that al-Abdulmohsen was a supporter of the anti-immigrant Alternative for Germany (AfD) party.
Mrs. Mina Ahadi, who is the chairwoman of the association for ex-Muslims in Germany, told the German newspaper Tageszeitung that the suspect is known to the organization and tried to send money about eight years ago.
He recalled that his behavior was “aggressive” and said that he felt as if he was “dealing with a mentally ill person”.
Ahadi wrote on X on Saturday that al-Abdulmohsen has “terrorized” the council for several years.
“His delusional thinking went so far as to think that even organizations that oppose Islam were part of the Islamic conspiracy,” he said.
What did the elders say?
The German Interior Minister, Nancy Faeser, told reporters on Saturday: “At the moment, what we can say with certainty is that the perpetrator was an Islamophobe. We can already confirm that. Everything else has to be investigated.”
On Sunday he said the attacker was “unlike the past” because he “acted like an Islamic terrorist despite being an enemy of Islam”.
The parliamentary committee meetings will be held on December 30 on the conspiracy in which Faeser and the leaders of German and foreign law enforcement will answer questions, a senior prosecutor told the AFP news agency.
What was the suspect's motive?
Magdeburg prosecutor Horst Nopens said on Saturday that one thing that is causing the suspect to be frustrated is Germany's treatment of Saudi refugees.
The suspect had made death threats against German citizens online and had a history of confrontations with authorities.
According to a Der Spiegel newspaper report that quoted security sources, the Saudi secret service warned the Federal Intelligence Service (BND), Germany's foreign intelligence agency, a year ago about al-Abdulmohsen's tweet warning that Germany would face consequences. support for Saudi refugees.
In August he wrote on social media: “Is there a way to get justice in Germany without blowing up the German embassy or killing German citizens at random?… If anyone knows, please let me know.”
Citing security sources, Die Welt newspaper reported that the German government and state police conducted a “risk assessment” on al-Abdulmohsen last year but confirmed that “there was no problem”.
What else is known about the suspect's intentions?
Felix Neumann, a German security policy adviser at the Konrad Adenauer Foundation, told Al Jazeera that he initially thought it was “an Islamic attack because it was very similar to the Breitscheidplatz attack in 2016” where a car was driven into on Christmas Day. market in Berlin, killing 13 people.
“If we look at what he said online, however, it is unlikely that it was an Islamic attack,” Neumann said.
“The perpetrator was very critical of Islam and shared fake news on his X account. Further investigation shows what motivated him in the end, but the concept of 'salad bar extremism' may apply here.
“This means that each person individually chooses what is right for them, but there is no uniform, unified opinion.”
Could the government have done more to stop the attack?
Neumann said: “Germany is a federal system, which has various advantages, but knowledge sharing is not one of them.
“Foreign law enforcement agencies and people who provided information about the threat to the criminal should be investigated, and it should be determined where there were errors in the sharing of information.
“This needs to be improved so that the assessment of potential threats can be carried out effectively among the authorities.”