Confessed Nazi hitman Heinrich Boere went on trial Wednesday in the western city of Aachen, charged with the 1944 murders of three Dutch civilians in reprisal for partisan attacks.

The 88-year-old was brought into the courtroom in a wheelchair and had a doctor by his side as the proceedings began, but looked alert and attentive as he answered the presiding judge's questions with simple one-word responses.

The resident of Eschweiler, on the outskirts of Aachen, faces the possibility of spending the rest of his life in prison, if convicted of the killings of a bicycle-shop owner, a pharmacist and another civilian while part of an SS death squad code named "Silbertanne," or "Silver Pine."

Protesters outside the state court building held up black banners that read "No peace for Nazi criminals" and "Don't forgive, Don't forget." Jeers of "Nazis Out!" and "Nazi pigs!" broke out in the courtroom when two far-right skinhead supporters of Boere entered the viewing gallery.

However, the session was adjourned before lunchtime before the formal charges against Boere were read out after the five-judge panel said it needed time to consider a defense motion to have lead prosecutor Ulrich Maass removed from the trial.

The defense argued that Maass made statements to the Dutch and German press that called his objectivity into question, and Maass said he would need until Monday to respond to the allegations before the court.

"It's just about getting a fair trial," defense attorney Gordon Christansen told The Associated Press outside the courtroom.

Maass said the allegations were unfounded.

The delay meant disappointment for Teun de Groot, the son of one of Boere's victims — the bicycle shop owner — who joined the trial as a co-plaintiff as allowed under German law.

The opening of the trial was the first time he had ever seen in person the man who killed his father — the two sat about 20 feet apart on opposite sides of the courtroom — but he said he was not going to be able to personally attend in the future.

"I'm angry because of the tricks of the defenders," he said in broken English. "I wanted to make a statement to Boere and now it is not possible."

He said his attorney will instead read a statement from him, but refused to say what it was he wanted to say to Boere.

Boere admitted the three killings to Dutch authorities when he was in captivity after the war. He was sentenced to death in the Netherlands in 1949 — later commuted to life imprisonment — but Boere has managed to escape jail.

In 1983, a German court refused to extradite him to the Netherlands because he might have German citizenship as well as Dutch, and at the time Germany had no provision to extradite its nationals. Another German court refused in 2007 to make Boere serve his Dutch sentence in a German prison because he had been absent from his trial, having fled to Germany, and therefore unable to defend himself.

Efraim Zuroff, the top Nazi hunter at the Simon Wiesenthal Center — whose most wanted list had Boere at number 6 — applauded prosecutors for pushing to finally bring the case to trial.

"This sends a very powerful message that the passage of time in no way diminishes the guilt of murderers, and that old age should not protect the killers of civilians," he told the AP in a phone interview from Jerusalem.

"Boere's victims and their families are just as worthy of obtaining justice today as they were right after he committed his crimes."

The son of a Dutch man and German woman, Boere was 18 when he joined the SS at the end of 1940, only months after German forces had overrun his hometown of Maastricht and the rest of the Netherlands.

After fighting on the Russian front, Boere ended up back in Holland as part of "Silbertanne" — a unit of largely of Dutch SS volunteers like himself tasked with reprisal killings of their countrymen for resistance attacks on collaborators.

In statements after the war that are expected to form the basis for the prosecution's case, Boere detailed the killings almost shot-by-shot.

Boere's attorneys have declined to say how they will try to counter the confession, but could try to argue that their client was simply following orders.

"I don't want to talk here of the defense's strategy." Boere's attorney Christiansen said.

In a 2007 interview with the Dutch newspaper Algemeen Dagblad, Boere himself attempted to justify the killings, saying he was sorry for what he had done but that it was "another time, with different rules."

The trial is currently scheduled over 13 days through Dec. 18 but could last longer if more time is needed.