The aunt of a 12-year-old girl who was bludgeoned to death Aug. 5 in a wooded area in Fauquier County testified today at the trial of a 16-year-old youth charged in the slaying that she saw the defendant emerging from the woods moments after hearing "a smashing sound."

Marilyn Stewart said the noise sounded as if it had been made by rocks. Minutes later, family members discovered the battered and partly clad body of Melissa Lee Bushrod in a dry creek bed.

A Virginia State Police investigator testified today that he had found several bloody rocks near the girl's body; a prosecutor said one of them weighed 50 pounds.

The testimony came on the second day of Leon P. Smith's trial as an adult on murder, abduction and sexual battery charges in Fauquier County Circuit Court here. A second 16-year-old, Darren S. King, is scheduled to stand trial next month as an adult in the girl's death.

Fauquier Commonwealth's Attorney Jonathan S. Lynn told the jury in his opening statement that the rocks and other evidence he plans to present -- including a statement Smith made to police after his arrest -- would persuade them of Smith's guilt.

Smith's defense attorney, John W. Wine, asserted in his opening statement to the jury that even if Lynn is successful in producing the evidence he promised, the most it could prove is that Smith is guilty of a lesser charge, such as involuntary manslaughter.

"You've got some kids fooling around the rocks and they panicked and one girl winds up dead," Wine said. "What else happened we don't know."

Wine described Smith as a confused and frightened youth whose statements after being arrested must be discounted.

"Leon Smith did not even know what sex was," Wine said, attacking the sexual battery charge.

The defendant sat expressionless during most of today's arguments and testimony dressed in blue jeans and a bright red windbreaker.

Three of Melissa Bushrod's relatives testified that they had returned to their home in Morgantown, a tiny community near Marshall, after a brief shopping trip and were concerned that the girl was not at home baby-sitting with her younger brothers as she had been when the group left. Melissa lived at the house with her mother, grandmother, three brothers and aunt and uncle.

The aunt, Marilyn Stewart, said that shortly after the family began calling the girl's name, she heard the sounds from a thickly wooded ravine near the family's house. As the search continued, Stewart said, she saw Smith run from the woods and enter Darren King's house.

Stewart said the discovery of Melissa's body followed. "She was lying up on a bank side," Stewart said. "I sat down beside her and cried."

According to Sheriff's Deputy C. Hartman, "there was a lot of blood all over the place. The body was partially clothed.. . . Her fingernails were split . . . . "

Frances P. Field, an official in the Northern Virginia medical examiner's office in Fairfax County who performed the autopsy, testified the girl had suffered six severe blows on the head, all of them while she was still alive.

On Melissa's upper chest, Field said, there were wounds that appeared as though they were made by "the sole of a shoe." In addition, the body showed evidence of strangulation and severe damage to internal organs.

At one point, defense attorney Wine asked Judge W. Shore Robertson to dismiss the jury so he could argue that photographs of the death scene should be removed from evidence on grounds that they would unfairly repulse or inflame the jury. Robertson removed only some of the photographs in question.

Lynn is expected to finish presenting prosecuting witnesses today, after which Wine is expected to call defense witnesses.