A prime suspect in the Berlin Christmas market massacre has been identified as a Tunisian failed asylum seeker who was already on authorities' radar.
Anis Amri is the subject of an international manhunt after the attack left 12 dead and dozens injured.
The 24-year-old apparently arrived in Germany in July last year having left his home country for Italy in 2011 after the Arab Spring uprisings.
He applied for asylum in April and his claim was rejected in July, but he could not be deported because Tunisia initially claimed he was not a citizen and he did not have the correct papers to be repatriated, according to reports.
A European Arrest Warrant was said to show he used six different names under three nationalities.
After the manhunt was launched, reports emerged that Amri had been under surveillance earlier this year.
He was monitored for more than six months by German authorities after they received a tip that he may have been planning a break-in to finance buying automatic weapons for an attack.
But agencies stopped watching Amri in September after nothing was found to substantiate the original warning.
The operation was reportedly halted after turning up nothing more than him dealing drugs in a Berlin park and getting involved in a bar brawl.
However, officials said security agencies swapped counter-terrorism information about him as recently as November.
Reports on Thursday claimed Amri served four years for arson in Italy before he entered Germany.
One of his brothers was quoted by the Associated Press as suggesting that Amri may have been radicalised in prison in Italy.
Earlier, German interior minister Thomas de Maiziere said Amri was suspected of involvement in Monday's terrorist outrage but was not necessarily the man who drove the lorry into a crowded Christmas market in the German capital.
His identity papers were found under the driver's seat of the lorry, Der Spiegel said.