German officials have come under fire after it emerged Anis Amri, a suspect in the Berlin Christmas market attack, was known to police. His fingerprints were reportedly found in the truck that killed 12 people on Monday, Deutsche Welle reported on Thursday.

The suspect's fingerprints were found on the driver's side door of the Polish-registered truck, German public broadcasters NDR, WDR and the "Süddeutsche Zeitung" newspaper reported on Thursday.

The "Berliner Zeitung" newspaper also reported that traces of Amri's fingerprints were uncovered on the truck's steering wheel. 

If the reports are proven true, it would be the clearest evidence linking lead suspect Anis Amri to Monday's attack.

In their search for Amri, police raided a refugee shelter early Thursday morning in Emmerich and apartments in Dortmund where the Berlin Christmas market attack suspect reportedly lived prior to moving to the German capital, authorities said. 

German officials revealed on Wednesday that they had already been investigating the 24-year-old Tunisian months before Monday's rampage. 

Authorities even held him in a detention cell for a day and kept him under covert surveillance for six months before halting the operation. 

ID papers believed to belong to Amri were found under the driver's seat of a 40-ton truck that rammed through a crowded Christmas market in Berlin on Monday, killing 12 and wounding 48. Out of those injured, 14 remain in life-threatening condition. 

German prosecutors have issued a Europe-wide wanted notice for Amri, offering a 100,000 euro ($104,000) reward for information leading to his arrest. They have warned that the Tunisian could be armed and dangerous.

Source: MENA