HAGEN, Germany (AFP) - A German court on Wednesday halted proceedings against a 92-year-old former SS officer accused of the murder of a Dutch resistance fighter nearly seven decades ago.

In a case underlining the difficulty of trying elderly defendants for crimes of the Third Reich after so much time has passed, Dutch-born Siert Bruins, a German national, had been in the dock since September.

Presiding judge Heike Hartmann-Garschagen ruled after four months of hearings that because crucial evidence had been lost since the killing and key testimony was unavailable, it had been impossible to convict Bruins of murder.

"Proceedings will be halted," she said.

The ruling falls short of a formal acquittal but means that Bruins can leave court a free man.

Bruins was accused, together with another former member of the SS who has since died, of the murder of Dutch resistance fighter Aldert Klaas Dijkema in September 1944.

Prosecutors said Bruins or his accomplice shot Dijkema four times in the back after the resistance fighter was taken prisoner on a farm in the Netherlands.

They said that although it could not be proved that Bruins had pulled the trigger, he had made the murder possible and must be held responsible.

Bruins' defence team called Monday for a not-guilty verdict, pleading his innocence and arguing that the trial was unfair because the state had failed to produce any witnesses. They called the testimony from previous proceedings against Bruins contradictory.

Prosecutors in December demanded life imprisonment.

The nonagenarian, who lives in Breckerfeld in the west of Germany, was among about 30,000 Dutch citizens who collaborated with the Nazis during the occupation of the Netherlands.

He obtained German citizenship via the Fuehrer's Decree in May 1943 which conferred German nationality on all foreigners who worked for the Nazis.

Bruins was sentenced to death in his absence by the Netherlands in April 1949 for participating in three shootings, including that of Dijkema.

The sentence was subsequently commuted to life in prison.

He fled to Germany from where he escaped a Dutch extradition order in 1978 because Germany does not hand over its own nationals but was detained and sentenced by the German authorities in a different case.

In February 1980, he was handed a seven-year prison term in Germany for complicity in the murder of two Jewish brothers in Delfzijl in April 1945.

Another former SS officer, Heinrich Boere, was sentenced to life in March 2010 for the murder of three Dutch civilians and died in December in a prison hospital.