Fingerprints of Anis Amri, the Tunisian suspect in the attack at the Christmas market in Germany’s Berlin, have been found on the door of the truck that was driven through the crowd, Reuters reported on Thursday. Amri, a 23-year-old ex-convict who had been denied asylum in the country, killed at least 12 people in Tuesday’s incident. German Interior Minister Thomas de Maizier said finding his fingerprints on the vehicle strengthened their case.

Amri had provided multiple fake identities and nationalities in the past and is believed to have links to Abu Walla, a recruiter for the Islamic State group who was arrested in Germany in November. The attacker had entered Europe in 2012 through Italy and has been living on a temporary permit in Germany since 2015.

A Pakistani-national was arrested immediately after the attack as a suspect, but the police had later released him saying he was the wrong man. The Islamic State group claimed responsibility for the attack.