BUFFALO, N.Y. (AP) _ Mark O’Connor defended John Demjanjuk because he was convinced the retired autoworker couldn’t be the Nazi death camp guard who savagely beat Jews on the way to the gas chamber.

Demjanjuk was a gentle old man who’d bounce O’Connor’s 3-year-old daughter on his knee, smiling and talking nonsense.

O’Connor, a Buffalo lawyer who specialized in immigration law, moved to Jerusalem to defend the 68-year-old Ukrainian who lived in a Cleveland suburb. O’Connor had insisted it was a case of mistaken identity and warned that an innocent man should not be punished because of a desire for revenge.

That was five years ago. Today, O’Connor is pondering the man he thought he knew, the man who was convicted Monday in Israel of being the sadistic guard known as ''Ivan the Terrible.’'

''Toward the end, I looked at how calmly and cooly he removed me from this case after I fought for him for so many years believing in him, believing in his credibility,’' O’Connor said. ''I began to wonder whether I’d made a mistake.’'

O’Connor, who was the chief defense attorney until last year when he was removed by the Israeli court at Demjanjuk’s request, said the case against his former client was extensive.

The defense depended on creating a reasonable doubt about whether Demjanjuk was ''Ivan.’'

O’Connor tried to show that documents supplied by the Soviet Union linking Demjanjuk to the Nazis were forged. He also he tried to cast doubt on the testimony of witnesses, many of whom were old and in frail health.

The court, however, rejected the arguments.

''We determine decisively and without hesitation or doubt that the accused John Demjanjuk who is on trial before us, is Ivan, known as Ivan the Terrible, the operator of the gas chambers,’' said presiding Judge Dov Levine.

Levine’s summation indicated that the judges gave great weight to the testimony of five survivors who identified Demjanjuk as the Ukrainian guard at the Treblinka death camp in Poland.

The court also noted that Demjanjuk’s testimony was ''filled with inconsistent versions.’'

O’Connor acknowledged that Demjanjuk’s testimony was ''spotty,’' and said he understood how the judges could have conceived of Demjanjuk’s memory lapses as incriminating.

He said Demjanjuk chose not to prepare for cross-examination.

''It was one of the exceptions he took with the court and ultimately with his defense,’' O’Connor said.

O’Connor, who was asked to take the case by Demjanjuk’s daughter, was dismissed because of a dispute with Demjanjuk’s family and the Ukrainian community that supported him over the direction of the case.

''They (the family) didn’t understand the culture or country the way I did,’' he said of Israel. ''To explain why I was using a Talmudic argument to a religious judge sitting on the bench was something that became more and more difficult. ...

''They thought I was pro-Jewish,’' he said.

O’Connor said he thought it was irrational to attack the Holocaust survivors who are considered a national resource.

The attorney that replaced O’Connor as chief defender, Yoram Sheftel, changed the tone of the defense, trying to discredit the prosecution’s witnesses.

The tactic may have damaged the defense because it alienated public opinion, O’Connor said.

''The whole country was affixed to the trial and there was a sense that the judges knew they were deciding for the people,’' he said.

Showing respect and deference was the only way to keep people from viewing Demjanjuk as a ''symbol of past wrongs,’' he said.

Despite the emotionally charged atmosphere, O’Connor thinks Demjanjuk got a fair trial.

''It can’t be said that he (Demjanjuk) didn’t have every opportunity to present evidence,’' he said. ''He couldn’t have got a fairer trial.’'

Under Israeli law, Demjanjuk’s case will automatically be appealed and will probably be reviewed by the nation’s Supreme Court.

O’Connor said the court would give the case an extensive review and offer Demjanjuk another chance to cast doubt on whether he is ''Ivan the Terrible.’'