The man had attacked the police station with a meat cleaver and wearing a fake suicide bomb vest on Thursday - one year to the day after the Charlie Hebdo massacre. Police shot and killed the man after he approached the station and threatened officers.
French prosecutor François Molins said in an interview on Friday with radio broadcaster France Inter that the man had a German sim card in his cell phone.
Reports say that messages in both Arabic and German were also found on the phone.
The man, who had a printed Isis flag with him, has not been named publicly by authorities, but he has been identified in the French media as a 20-year-old from Morocco, who was known to French police for his role in a robbery, but had no known terror links.
Sources close to the investigation told reporters that police matched the man's fingerprints with those on file for the convicted thief, a homeless man who identified himself at the time as Ali Sallah, born in the Moroccan city of Casablanca in 1995.
Investigators are now trying to determine whether this is the man's true identity, with some reports suggesting they still have their doubts.
Molins said in the interview that the man had been identified as Moroccan during a police inspection some months ago, but he could not be sure that this was correct. A document found on his body states that he was Tunisian.
Authorities across Europe have been on high alert since the most recent Paris terrorism attacks on November 13th killed 130 people. In Germany, a threat of a terror attack in Munich on New Year's Eve led police to evacuate two train stations and tell revelers to avoid large crowds.
Police are still hunting for up to seven people suspected to be behind the threat.