It's taken five years, covers 1,798 pages, and its work still isn't finished. On Thursday, a second Bundestag investigative committee presented its final report on the botched investigations into a series of ten murders, three bombings, and 15 bank robberies carried out by the neo-Nazi terrorist cell that called itself the National Socialist Underground (NSU).

The report showed how Germany's intelligence agency, the Verfassungsschutz, systematically blocked investigations into the murders to protect their paid informants - all neo-Nazis who not only failed to provide information on the NSU, but used the taxpayers' money they were being paid to finance neo-Nazi activities.

Not only that, there were several glaring differences between what German prosecutors still believe and what the parliamentarians have concluded: that there were a number of failures in investigations both before and after the group was uncovered in 2011.

While federal prosecutors still say the NSU was a trio - Uwe Mundlos and Uwe Böhnhardt, both dead, and Beate Zschäpe, currently on trial in Munich - the committee believes the group was much bigger: There was evidence of "several direct and indirect acquaintances of the NSU terror group in local, regional, and national neo-Nazi scenes."

The NSU is accused of a series of ten murders

The report said that this support network was never properly investigated, even though it was very clear "which protagonists and networks had contact with Böhnhardt, Mundlos and Zschäpe at the individual scenes of their crimes."

Questions left unanswered

In 2012, Chancellor Angela Merkel vowed that all ten murders would be thoroughly investigated, but as the daily Süddeutsche Zeitung said on Thursday, that promise appears "fairly empty" five years on.

Zschäpe has been on trial in Munich since May 2013

The Bundestag committee has often voiced its concerns about the way Germany's domestic intelligence organizations obstructed their investigations. "We have a situation where central questions of the victims' relatives - Why was my husband, my brother, our daughter killed? - remain unanswered," said the Left party's Petra Pau, one of the authors of the report. "We had to deal with a lot of obstacles."

"It's been proven that the NSU's core trio was surrounded by at least 40 informants," Pau told DW. "The federal [domestic intelligence agency] always claimed that it had no informants with the NSU - that's complete nonsense."

The Green party's Irene Mihalic, another leading opposition member of the committee, said the Federal Office for the Protection of the Constitution (BfV) had worked quickly to sabotage attempts to find out who these informants were and what they knew.

"We worked out that the destruction of files on November 11, 2011 [a week after Zschäpe's arrest] in the federal office of the [BfV] was deliberate and specific," Mihalic said in a statement. "It was not to be publicly known that the trio had virtually been surrounded by informants in the 1990s."

Petra Pau said there needed to be fresh inquiries after the German election

The conclusion: "Our research makes more than clear that the neo-Nazis probably profit more from the informants than the security forces and, therefore, society at large."

Read more: Germany's domestic security services explained

Leads not followed

There were bewildering connections and coincidences that the BfV failed to follow up: murders happened within a few meters of bars known to be frequented by local neo-Nazis - but no one thought to question them partly because the police assumed that the murder of Turkish-Germans must be the work of Turkish organized crime.

One murder in the series of ten has received particular attention - that of police officer Michele Kiesewetter in Heilbronn in 2007. The Bundestag committee wondered why, despite the fact that six DNA traces found in the area have yet to be identified, the murder investigation was suspended in 2011.

Some of the victims' families have sued the German security forces

The fact that Kiesewetter did not have an immigrant background has led to speculation about why she was targeted by the terrorists. "That question is, for us, unanswered," said Pau. "The federal state prosecutor is talking about a random victim. We, across all parties, think that's an untenable theory. Not only that, it's utterly wrong that not all information that could have been collected about those present at the crime scene on that day was collected and investigated - for instance, mobile phone data located at the time."

Scrap the Verfassungsschutz?

Most of Germany's main political parties have called for reforms in Germany's security forces following the revelations, but as far as the Left party is concerned, the rot is much too deep: the only reform of the domestic security service that would work is its complete abolition.

"Firstly, secret services are an alien element in a democracy," said Pau. "But this Federal Office for the Protection of the Constitution and its state counterparts have shown that they were unable to prevent a single attack. There was knowledge of the NSU trio; there was knowledge that they acquired weapons, that they wanted to carry out attacks. All this information was available to the security services but never reached the criminal prosecution authorities."

The Left party wants to see a new observation center set up - without informants. "These people aren't responsible citizens out to bring information to the state - they're violent, militant Nazis," Pau said.