The German authorities have some serious questions to answer. A neo-Nazi cell managed to operate under their noses for 11 years, murdering nine Turks, a Greek and a policewoman without investigators realizing that they were dealing with ruthless terrorists.

It seems that German detectives were guilty at best of gross incompetence or at worst, institutional racism. For some years the crimes were ascribed to rivalry within the Turkish community. Journalists variously dubbed the murders “the Bosphorus slayings” and the “Kebab Killings”.

But in fact the crimes were being committed by three white terrorists who called themselves the “National Socialist Underground”. They were unmasked not by an intensive anti-terrorist dragnet but as a result of the last of 15 bank robberies which the killers for once bungled. Police were able to trace two of the gang to a caravan in which the terrorists, though heavily armed, shot themselves rather fight it out and risk bing captured.

The third neo-Nazi, a woman, tried to burn out the apartment that she shared with the other two killers, but failed to destroy key evidence including the Czech pistol and silencer used in all the murders and a propaganda recording in which the gang boasted of their crimes. This woman, Beate Zschäpe, later handed herself in to the authorities. This week, at the end of a five-year trial, she was found guilty of all the killings and faces an automatic life sentence.

Berlin is mounting an inquiry into how these terrorists could have escaped detection for so long. Of particular importance will be the basis on which police decided the nine murdered Turks were victims of their own community. What was the evidence that led investigators to a conclusion that has now proved to be so obviously wrong? When an ethnic Greek was gunned down in 2005, in the middle of the seven-year murder-spree with the same weapon, why did not the police ask themselves if they were actually on the right track?

A failure no less egregious was the failure of the investigators to assign an ethnic Turk to the inquiry team. Even the murder of a fellow police officer, again with the same gun, does not seem to have caused the detectives to change their strategy. This policewoman was the last of the terrorists’ victims. In 2007 she was shot dead in her vehicle and a colleague, who survived, was hit in the head.

But the inquiry floundered on for another four years before the failed bank robbery handed the police the answers they had failed so pathetically to uncover for themselves. Perhaps the most damning question they must answer is why there was never a strand in their investigation specifically aimed at exploring the possibility of a neo-Nazi connection.

The sheer inefficiency of the German authorities is breathtaking. There appears to have been no peer review of these long-running cases by independent officers. Indeed, there seems to have been little sense of urgency among those charged with detecting the perpetrators of these crimes. It is hard to put aside the suspicion that institutional racism was at work here. The victims were nearly all Turkish Muslims and as such their killings did not merit the same level of investigation that would have been given to the murder of nine white Germans.