A Columbia University graduate student who was raped and tortured during 19 hours of nightmarish sadism pointed out the man who is on trial for the attack as the one who drove her to ask for death and try to kill herself.

Her eyes unblinking and her jaws tightly set, the 24-year-old woman pointed directly at Robert Williams in court yesterday when asked if she saw her attacker in the courtroom.

The woman identified him as she resumed testimony she had begun Friday to describe an almost unimaginable ordeal of searing pain, degradation, and fear at the hands of her attacker.

Williams, a 31-year-old ex-convict who had refused to come to court Friday but was forced to appear yesterday, stared straight ahead.

Williams lawyer, Arnold Levine, agreed that the identification hurt the defendant although Williams has offered no discernible defense. “It’s always damning when a witness identifies your client,” he said.

Mr. Levine had no questions for the witness after her direct testimony.

The witness described at least seven instances of rape, sodomy, and forced oral sex over the 19 hours her assailant was in her apartment in upper Manhattan’s Hamilton Heights section.