(Vatican Radio) A Europe-wide manhunt is under way for a Tunisian man wanted for Monday's truck attack on a Christmas market in Germany's capital Berlin that killed at least 12 people and injured almost 50 more.
According to German media, the Polish truck driver could have been kidnapped and told to drive the vehicle into the crowd before resisting and being killed.
"He spent four years in jail in Italy where he met extremist groups, which attracted him", Amri's father told The Times.
He wound up there after fleeing from Tunisia in 2011, one of thousands of young Tunisians who made the journey during the Arab Spring. "If it is proved that he is involved, we dissociate ourselves from it".
Abdelkader said the whole family was "in shock" and struggling to come to terms with the possibility his brother may be behind the massacre.
"If he's guilty, he deserves every condemnation", he told the AFP news agency.
"We all need to be ready to implement practical solutions", Merkel said when introducing the idea.
He also said the man had applied for asylum, but his request was turned down.
Both attacks and in Nice and Berlin have been claimed by the Daesh (ISIL) Takfiri terrorists.
The terrorist group is known to target young criminals with propaganda offering redemption through jihad, in what analysts call an emerging "crime-terror nexus".
But Amri didn't have a valid passport, and Tunisia refused to acknowledge him as a citizen and give him fresh papers.
The necessary paperwork did not arrive until Wednesday.
In a revelation likely to stoke public anger, German officials said they had already been investigating Amri, suspecting he was planning an attack.
There were also raids at a migrant centre in Emmerich in western Germany, where Amri stayed briefly past year, and at addresses in Berlin.
Adding to the troubling list of questions is the fact that Amri was known as a unsafe offender in Italy and was considered a threat by the United States. Walaa (real name: Ahmad Abdulaziz Abdullah) was arrested in November in an anti-terror raid on charges that he was recruiting ISIS fighters.
German media reported several locations were searched overnight, including a refugee home in Emmerich on the Dutch border.
Named the prime suspect, a 100,000-euro reward has been offered for information leading to his capture, making him Europe's most wanted man.
The technique has previously been used by Isis militants including the Paris and Brussels attackers in attempts to throw authorities off their scent.
The Breitscheidplatz reopened at 11 a.m. local time (5 a.m. ET), three days after the attack in Berlin that also left nearly 50 injured, many of them seriously.
Since the attack, Merkel has been hit with sharp criticism from the far-right Alternative for Germany (AfD) party over her open-door policies that allowed more than a million refugees into the country during the last 16 months.