AN 88-YEAR-OLD suspected mass murderer who hunted down Slovak partisans and British agents during the Second World War walked free from a Munich courtroom yesterday after the collapse of probably the last big war crimes trial in Germany.

Ladislav Niznansky staggered slightly when the judge declared that there was insufficient evidence to convict him of killing 164 Slovak villagers and fugitive Jews. The prosecutor had demanded that he be jailed for life.

The release of Herr Niznansky — a captain in the notorious German-led Edelweiss unit — is likely to mark the end of the active prosecution of suspected wartime murderers. The witnesses are too aged and their memory too erratic, and the paper trail is too inconclusive to guarantee a conviction. Lawyers say that state prosecutors will now hesitate before pursuing other Nazi cases that are under investigation.

During the 15-month trial of Herr Niznansky, witness testimony crumbled under rigorous cross-questioning. Much of the evidence against him had been gathered by the Czech secret police during the Cold War.

But his defence team demonstrated that evidence could have been manipulated by the communist authorities to blacken the name of Herr Niznansky, who was a fierce anti-communist who worked after the war as a journalist for Radio Free Europe. The turning point for Judge Manfred Götzl came when a 79-year-old witness, Jan Repasky, mixed up crucial names and dates. Herr Repasky, a former railway worker, claimed to have seen Herr Niznansky shoot 20 victims, but his account failed to convince the judge.

The prosecution had to establish that the murders, in three Slovak mountain villages, were carried out under Herr Niznansky’s orders. Unlike other suspected Nazi criminals, the former journalist (a German citizen since 1996) did not feign senility. Instead, he argued that fighting against partisans was a legitimate cause.

The mission of the Edelweiss unit was to destroy resistance to German occupation. Herr Niznansky was a 27-year-old captain and argued during the trial that, as a Slovak, he could not have ordered Germans to shoot to kill. He regretted his involvement in the unit but said that he had been given the choice of fighting in the unit or being sent to a concentration camp.

• Scotland Yard is still investigating allegations that Herr Niznansky’s unit tortured and executed Major John Sehmer, of The Royal Tank Regiment, and four other members of the Special Operations Executive who parachuted into Slovakia.