Historians questioned two previous "guilty" verdicts against suspected Nazi war criminal Sandor Kepiro at his trial in Hungary on Thursday.

Kepiro -- possibly one of the last Nazi war crime suspects to be tried -- faces a life sentence for his alleged participation in a raid by Hungarian forces on Novi Sad between January 21 and 23, 1942, in which more than 1,200 Jews and Serbs were murdered.

Specifically, Kepiro is accused of ordering the rounding up and execution of 36 Jews and Serbs while head of one of the patrols involved in the raid.

The 97-year-old has already been found guilty of the crimes twice before.

A first 10-year jail sentence dating back to 1944 was quashed, but Kepiro was convicted again and sentenced to 14 years in 1946 in a showcase trial by the communists.

Kepiro avoided prison by fleeing to Argentina where he remained for half a century before returning to Budapest in 1996. That was where the chief Nazi hunter of the Simon Wiesenthal Center, Efraim Zuroff, tracked him down 10 years later.

Two expert witnesses who took the stand on Thursday queried the validity of the previous two verdicts.

Historian Tibor Zinner argued there were numerous errors and omissions in the translation of a number of the court documents, thus casting doubt on their reliability.

Another historian Sandor Szakaly suggested it was not certain whether the executions for which Kepiro is charged were committed by the military or by the gendarmerie.

The suspect was a former gendarmerie officer.

"Judging by the large number of victims, the use of military execution units is plausible and the gendarmerie were not allowed to take part in these," Szakaly said.

In addition, the uniforms of soldiers and the gendarmerie were very similar and could therefore be easily mistaken, the expert argued.

Like fellow historian Zinner, he, too, suggested the documents from the previous trials were "neither reliable nor authentic."

The Simon Wiesenthal Center said it would call a witness who was eight years old at the time of the raid and who claimed to have seen Kepiro beating a boy.

The court will decide on Friday whether that witness will be heard.