The German Police has now revealed some information about Anis Amri;

A wanted notice was issued by the German Federal Prosecutor’s Office, which stated that a reward of up to 100,000 euros (about $104,000) was offered for information about the suspect’s whereabouts, and said Amri is “under urgent suspicion.” The notice also said, “If you see this person that we are seeking, inform the police. German police, who considered Amri dangerous and suspected he was part of a large Islamic extremist network, first launched an investigation against him on March 14 following a tip from federal security agencies that he may have been planning a terror attack. Police in Berlin are offering a reward of €100,000 (US$104,260) for information leading to the arrest of the man suspected of involvement in Monday’s attack on a Christmas market which left 12 dead and 48 injured. In Duesseldorf, Ralf Jaeger, interior minister of the western state of North Rhine-Westphalia (NRW), said the Tunisian appeared to have arrived in Germany in July 2015 and his asylum application had been rejected. “Beware: He could be violent and armed!” the prosecutor’s office said in a statement, in which it described Amri as 1.78 metres (5’8”) tall, with black hair and brown eyes.
German officials offer a reward of up to 100,000 euros ($104,000) for 24-year-old Tunisian asylum-seeker Anis Amri, whose identifying information was found in the truck used in the attack.