A Montgomery County Circuit Court jury, apparently deeply moved by the poignant testimony on Monday of a 5-year-old girl, deliberated just 33 minutes yesterday before finding the girl's father guilty of sexually abusing her and her severely retarded 8-year-old sister.

Their 32-year-old mother broke into sobs in the front row of the courtroom when the jury foreman said the panel had found the man guilty of two counts of child abuse, one for each daughter. The 35-year-old father stood motionless, showing no reaction.

The man, who neither testified nor presented evidence in his own defense, faces up to 30 years in prison for molesting the two girls. Judge DeLawrence Beard scheduled sentencing for April 19.

The daughter who testified "was the whole case," a juror, who requested anonymity, said afterward. "She's what swayed me. Without the little girl, it was just the mother's word against the father's."

The juror, a 38-year-old father of two boys, said he would encourage his own children to testify in court if they ever were sexually molested.

Outside the courtroom after the verdict, the mother hugged and thanked several of the women jurors and Assistant State's Attorney John McCarthy, who prosecuted the case.

"My family is better off -- now my kids are protected," she said. "I don't have any feelings left anymore for my husband . I don't hate the man, I just don't feel anything. He's a very sick man."

For the little girl, testifying was at once cathartic and terrifying, according to her mother.

"In the past, her daughter hadn't talked about it -- now she is talking to me about it; it's all coming out." But, she added, after testifying, her daughter awoke Monday night terrified by nightmares similar to those she experienced after her father was arrested last June.

Both children are in therapy, the mother said. The family's name is not being used in order to protect the daughters' identities.

All seven women on the jury declined to discuss their reactions to the testimony of the girl, who is the youngest child ever to take the witness stand in a Montgomery courtroom, officials said.

"It was a very emotional case for all of us and I don't think any of us want to talk about it," said one woman who did not wish to be identified.

McCarthy said in closing that the girl was too young to realize that what her father was doing to her was wrong until after her mother and other adults expressed shock over the man's action.

"She didn't know to be afraid before," McCarthy said of the child, whose picture he kept propped up on the prosecutors table throughout yesterday's proceedings.

"This case is a microcosm of the horror of child abuse. Here is the young innocent child and all she has is love . . . She loved her daddy and daddy loved her but he hurt her," he told the jurors. "Ladies and gentlemen, the time has come for you to speak for these children."

Cleopatra Campbell, the defendant's attorney, told the jury that 5-year-olds cannot be believed. "They dream things up," she said. "She is a beautiful child, but is she worthy of convicting this man?"