Evidence has emerged in Germany that politicians were warned nine months before Berlin's Christmas market massacre that Islamic State disciple Anis Amri was plotting carnage.
The State Criminal Office in North Rhine-Westphalia made Tunisian-born Amri's lethal intentions known to authorities in March 2016, reports the Daily Mail.
But the bogus asylum seeker remained at large until December 19 when he hijacked a Polish lorry and drove it into a crowd of revellers in Berlin, killing 12 and injuring dozens more.
Amri, 24, fled across Europe to Milan, Italy, where he was shot dead by police five days later.
It was known that Amri had moved in and out of the radar of police and intelligence services during his time in Germany.
But now a letter has surfaced written in March last year to the ministry of the interior of the state parliament in Duesseldorf which stated: "Amri presents a threat in the form of a suicide attack. The commission of a terrorist attack by Amri is expected."
The letter went on to suggest deporting him and contained evidence of a tapped phone conversation in he had in February in which Amri used the word 'Dougma' - a metaphor, say German spies, that Islamists use to mean a "suicide bombing".
The deportation was never arranged because the North Rhine-Westphalian authorities concluded that expulsion was unenforceable.
And additionally, Amri claimed to have no passport and Germany could not send him home because Tunis denied he was a citizen until the day after the killings.
Even after the attack, regional Interior Minister Ralf Jager several times said it was not "legally possible" to order a deportation.
The new details are a further embarrassment to the government whose intelligence services are struggling to contain terror threats from Islamic fanatics who smuggled themselves into the country disguised as refugees.
Jager, a left wing politician, has been blasted as a security risk for Germany by rival conservatives for failing to pass on the details of the threat.
Armin Laschet, chief of the CDU conservatives in the state, said: 'He presents a risk for everyone in Germany.'
The Liberal FDP party is calling for his resignation.
Jager will testify before a parliamentary committee of inquiry on Wednesday about his failure to act on the police warning.
Earlier this month, German authorities raided apartments linked to a mosque in the city of Hildesheim visited by Amri.
The local state interior ministry said more than 300 police searched the apartments of eight people and shut down the mosque and the association which ran it, saying it recruited young Muslims to join Islamic State militants in Iraq and Syria.
"The ban of the association breaks up a hot spot of the radical Salafist scene in Germany," Lower Saxony Interior Minister Boris Pistorius said, referring to Muslims who espouse a strict interpretation of Sunni Islam.
Authorities raided the mosque in the summer of 2016 over suspicions that it was radicalising Muslims and encouraging them to travel to war zones in Syria and Iraq.