Cook County Circuit Court Judge Richard L. Samuels today sent convicted rapist Gary Dotson back to prison, saying that he does not believe the dramatic testimony of Dotson's alleged victim that she lied six years ago about being raped in 1977.

Samuels, who presided over Dotson's trial in 1979, said the reversal by Cathleen Crowell Webb lacked "sufficient corroboration."

Webb, who identified Dotson as her assailant in that trial, sobbed, "He's innocent!" as she left the packed courtroom at the end of the second day of testimony surrounding Dotson's petition to be set free.

Samuels based his decision on his perception at the 1979 trial that "her testimony was clear and convincing" and that her "demeanor was consistent with a person making a sincere charge of rape," he said.

By contrast, he said, her demeanor last week when she testified that the rape never happened "did include what might be called a selective recollection."

"The bottom line," he said, was the 1979 jury finding of guilty, after 96 minutes of deliberation.

He criticized today's testimony by a friend of Dotson who sought to provide him an alibi for the night of the alleged attack in July 1977, saying the witness "wrought havoc with the claim of an alibi."

He was referring to inconsistencies in the story told by William Julian, who said he, Dotson and several friends were together that night.

As to Webb's change of stories, Samuels said, "I don't know for what reason" Webb took the stand and recanted.

Webb had attributed her actions to her religious faith and a desire to make things right.

The emergency-room physician who examined Webb on the night she reported the rape testified today that her injuries were superficial. He said he had advised her to "apply ice packs" to the bruises on her head and arms and take aspirin if needed, but prescribed no drugs for what was described at the time as her "hysteria."

The physician, who testified for the prosecution at the trial, said today that a vaginal smear taken the night of the reported attack, plus two other tests, showed "no evidence of sperm cells" and no evidence of semen anywhere on Webb. That testimony was not included in the 1979 trial.

He said this could mean, among other things, that "no sex act was committed," that the act was not consummated, or that the attacker was sterile or had had a vasectomy.

Dotson had watched attentively while witnesses called by the state described Webb's tearful and trembling demeanor on the night she reported the attack.

In addition to the inconsistent stories by Dotson's alibi witnesses, the state presented laboratory evidence that it said strongly indicated that Dotson was the assailant.

Webb testified that she made up the story because she feared she was pregnant after a sexual encounter with her boyfriend and did not want her foster parents to know.

In closing argument, Dotson's attorney noted that at the 1979 trial four persons testified that they knew of Dotson's whereabouts when the rape supposedly happened, that two other alibi witnesses testified today that Dotson's clothing was nothing like that worn by the man Webb described and that the picture she had a police artist draw of her attacker showed no mustache, while Dotson had one. He also said the scratches Webb claimed she inflicted on her attacker were not present on Dotson when he was arrested.

Dotson, 28, has served six years of a 25- to 50-year sentence.