After more than two years and 200 days of hearings, Germany’s most high-profile neo-Nazi trial is heading into uncertain waters and an even more uncertain verdict.

A Munich judge has refused an application by three public defenders to be released from their duties representing Beate Zschäpe, the surviving member of the extreme-right National Socialist Underground (NSU).

The 40-year-old is standing trial for murder over alleged involvement in a terrorist campaign behind the deaths of eight Turkish-born immigrants, a Greek national and a German policewoman.

Only in 2011, four years after the last killing, were the crimes – carried out all over Germany – linked as the work of the previously unknown NSU. The group’s other two members, Uwe Mundlos and Uwe Böhnhardt, died in an apparent murder-suicide after a botched bank robbery, through which they financed their campaign.

Ms Zschäpe blew up their last hideout and tried to escape but was arrested and has been in custody since 2011. She has stayed silent since her high-profile trial began in May 2013 under tight security in Munich.

In recent months Ms Zschäpe has complained to the court that she has no confidence in her trio of court-appointed lawyers and filed an application with the court for them to be replaced. She accused them of only going through the motions to defend her in court and of leaking sensitive documents to the media.

The court refused her request but appointed a fourth lawyer to the defence team. On Monday the original three court-appointed lawyers – Wolfgang Heer, Wolfgang Stahl and Anja Sturm – filed their own application to leave the trial. In recent weeks trial attendees say the lawyers and their client are no longer speaking to each other.

The Munich court adjourned proceedings on Monday to consider the request before issuing a refusal, saying it could see no formal reason to grant the release. Legal experts say it was unclear whether the case could continue with new defence lawyers or whether granting the application would force a mistrial.

“It could also mean that, if the trial continues with the current defence, that the defendant has a reason at the end for appeal,” said one of the defence lawyers, Mr Stahl, ahead of the ruling, “by saying she was not defended adequately, at least not in the last phase when we said we couldn’t defend her properly”.

A collapse of the trial would be a further disaster for German authorities who have vowed to do everything in their power to investigate the NSU campaign, the longest serial killing campaign in post-war German history.

An 18-month parliamentary inquiry into the NSU affair blamed institutional incompetence “without parallel” for allowing the organisation to operate without detection for more than a decade.

The inquiry’s 1,000-page report said overlapping police structures and institutional rivalry between investigators in various federal states meant that crucial information was not shared – in particular that the same gun was used in all 10 murders.