Investigations "over the past two weeks have brought no indications of any Islamist network" connected to the man, said Uwe Jacob, police chief of North Rhine-Westphalia state.
The attacker, identified as Tarek Belgacem by Tunisian authorities, was shot dead by French police as he attempted his assault on January 7 - the one-year anniversary of the jihadist attack on satirical weekly Charlie Hebdo in Paris.
