Richard Lambert, chief of the criminal division of the U.S. Attorney's Office, made the revelation about the presumed death of Kiplyn Davis at a pretrial hearing for Timmy Brent Olsen, who goes on trial Monday for allegedly lying during an investigation of the 15-year-old's disappearance.

He said evidence of how Kiplyn died came up in testimony before a grand jury looking into the case.

Lambert did not specify who produced the evidence or who might have struck the fatal blow.

Kiplyn, a sophomore at Spanish Fork High School, disappeared after her lunch break on May 2, 1995. She has never been located.

After an initial investigation, the case seemed stalled. In the spring of 2003, the girl's parents approached then-U.S. Attorney Paul Warner, who convened a federal grand jury and revived the probe.

Olsen and four other men, most of them former classmates of Kiplyn, were indicted in 2005 on charges that they lied to police or the grand jury during an investigation into the disappearance. Each count carries a maximum penalty of five years in prison.

Two of the defendants, Garry Von Blackmore, 26, and Scott Brunson, 29, have pleaded guilty and are scheduled to be sentenced in June.

Separate perjury trials of David Rucker Leifson, 29, and Christopher Neal Jeppson, 29, are slated to begin in the summer.

Olsen, a 28-year-old Spanish Fork mechanic, originally was charged with 20 counts of perjury, but prosecutors later obtained a superseding indictment that streamlined the charges to 17. U.S. District Judge J. Thomas Greene, who will be presiding over the trial, on Thursday dismissed another count after defense attorney Stephen McCaughey argued that it centered on the same conduct in another charge.

When the federal trial is completed, the Utah County Attorney's Office will try Olsen on a charge of murder, a first-degree felony, in Kiplyn's death. If convicted, he could get a life sentence.

The perjury indictment alleges that Olsen lied when he denied he ever said he killed Kiplyn or knew where her body is, skipped classes with the girl the day she vanished or asked Brunson to provide him with a fake alibi.

In addition, he is accused of lying about whether he ever forced a woman to have sex with him, whether he ever assaulted his wife and whether he hit a girl over the head with a flashlight in Oak Creek Canyon when she resisted his sexual advances.

McCaughey unsuccessfully argued at the hearing that there should be a separate trial on the charges involving women other than Kiplyn. He pointed out that Olsen is being tried on perjury charges and said including the assault allegations in the same trial would be unfairly prejudicial.

But Lambert countered that the grand jury started its investigation on the basis that Kiplyn's disappearance was a possible kidnapping and murder. Witnesses told the grand jury that Olsen told them he had killed the girl, and questions about the incident in Oak Creek Canyon, which is similar to what might have happened to Kiplyn, were relevant to the probe, he said.

Richard and Tamara Davis, the girl's parents, attended the hearing. Afterward, Richard Davis said it was tough to hear some of the evidence, but he and his wife will sit through the trial.

"I know it's going to be hard, but we're going to be strong," Davis said.

pmanson@sltrib.com