A dogged German prosecutor has charged an 86-year-old man with three wartime murders of which he was originally convicted almost 60 years ago.

Dortmund prosecutor Ulrich Maass told a news agency that he has charged Heinrich Boere with the murders in 1944 of three Dutch civilians when Boere was a member of a death squad code-named Silbertanne (Silver Pine).

Boere was convicted of the same murders in 1949 in the Netherlands. A death sentence was later commuted to life imprisonment but he has managed to stay out of prison ever since.

The prosecutor has now filed the charges once again in a final attempt to bring Boere to justice. It was not immediately clear when Boere might be brought to trial, said his lawyer Gordon Christiansen, who would not comment on the charges, saying he had not yet seen the official documents.

The Netherlands had sought Boere’s extradition, but in 1983 a German court refused on the ground that he might have German citizenship. At that time, Germany had no provision to extradite its nationals.

A state court in Aachen, in western Germany, ruled in 2007 that Boere could legally serve his sentence in Germany.

But an appeals court in Cologne overturned the ruling, saying the 1949 conviction was invalid because Boere was unable to present a defence. After this, Herr Maass quietly reopened the case from scratch.

The son of a Dutch man and German woman, Boere was 18 when he joined the Waffen SS — the fanatical paramilitary organisation faithful to Hitler’s ideology — at the end of 1940, only months after his country had fallen to the Nazi blitzkrieg.

After taking part in the invasion of the Soviet Union, he ended up back in the Netherlands as part of Silbertanne, a Waffen SS death squad composed mostly of Dutch volunteers. They had the job of killing fellow countrymen in reprisal for attacks by the resistance.

The unit was suspected of a total of 54 killings and Boere has admitted to taking part in three, according to Dutch court documents.