Special investigator Bruno Jost has completed his report into the police actions surrounding Berlin terror attacker Anis Amri and said officers should have been able to stop Amri before the attack took place, noting they only monitored him “sporadically”.

Mr. Jost, a former German Federal prosecutor, slammed the methods of the Berlin State Criminal Police Office (LKA) officers saying in his 72-page report that officers were “inadequate”, “belated”, “failing”, and “unprofessional”. The special investigator said that if police had done their jobs properly, there was a “high probability” the attack could have been thwarted, Der Spiegel reports.

One of the most damning findings of the report was that LKA officers only kept an eye on failed Tunisian asylum seeker Amri on weekdays and did not bother to watch what he was doing on weekends or holidays.

Jost said that while Amri’s radical Islamic activities were not serious enough to put him behind bars, LKA investigators squandered an opportunity to arrest and deport him in connection with his drug dealing activity.

The reason Amri was never prosecuted for drug trafficking, according to the report, was a total lack of communication between branches of the police and the prosecution services. In the end, no service wanted to be responsible for Amri and his case never proceeded to court.

The Berlin authorities were not the only ones deeply criticised in the report. According to Jost, when Amri was in Baden-Württemberg he was caught in possession of a pair of fake Italian ID cards. Despite it being a crime, Amri was released by authorities in Friedrichshafen without charge.

Anis Amri: Small-Time Criminal Turned Berlin Truck Killer https://t.co/lOgzohvybL pic.twitter.com/lUIe1ELoC8 — Breitbart London (@BreitbartLondon) December 23, 2016

Jost is also currently investigating allegations that LKA officers tampered with evidence relating to Amri in order to cover up their own failures and mistakes. Mr. Jost has accused an unnamed police commissioner of having tampered with the files as they were the last person to log on to the computer where the files were kept.

Failed Tunisian asylum seeker Anis Amri killed a dozen people and injured almost a hundred others after he rammed a truck into a crowded Christmas market in Berlin in December. He went on the run after the attack but was later shot dead in Italy by armed police.