The latest version of their file on Amri, which included information on his eight different identities, was updated on December 14 -- just five days before he rammed a truck into a crowded Christmas market in Berlin.
Duesseldorf police deemed him a Salafist and radical fundamentalist, while Dortmund police had rated him a sympathiser of the Islamic State group.
Amri had been a regular guest at a religious school in a Dortmund apartment run by a notorious radical known as Boban S. that was believed to be a recruitment ground for jihadists.
Nevertheless, on an eight-point scale assessing an individual`s potential danger, with "one" the highest threat, counter-terrorism experts rated him a "five" -- meaning they considered an attack possible but unlikely.
Shortly after the Christmas market rampage, authorities admitted that counter-terrorism services had been watching Amri, suspecting he may have been plotting an attack.
But surveillance was dropped in September, as police thought he was primarily as a small-time drug dealer.
Chancellor Angela Merkel ordered a sweeping review of the security apparatus after the attack, so that any necessary reforms could be agreed and implemented quickly.
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