Four years after the beaten and strangled body of Beverly R. Mitchell was found in a field near La Plata, the trial of a man accused of killing her is to begin tomorrow in Charles County Circuit Court.

Circuit Court Judge Richard J. Clark declined in a pretrial hearing Wednesday to dismiss murder and other charges against Garrison Thomas, 44, of Washington.

The judge rejected public defender Carl W. Buchheister's argument that prosecutors waited too long after Mitchell's 1995 death to bring a case against Thomas, who was indicted in December. Witnesses who might contradict prosecutors' versions of events have disappeared in the meantime, Buchheister said.

Assistant State's Attorney Matthew R. Stiglitz said the indictment resulted from time-consuming and intensive reexamination of evidence in the case.

Clark ruled that the defense had not shown that authorities had delayed prosecution in order to gain an advantage.

The finding clears the way for a jury trial that is expected to last at least five days, according to attorneys on both sides.

Thomas is charged with first-degree murder and kidnapping. He also is accused of robbery and theft -- charges that relate to Mitchell's car, a Mitsubishi Eclipse that was found in Washington after her slaying.

Mitchell, 26, of Alexandria, was a customer service representative for a mutual fund agency in Bethesda. She was last seen alive on March 22, 1995, in Southeast Washington, as she left the home of her aunt and uncle.

The following day a youth looking for a place to drive off-road vehicles found her body on a clear-cut tract that has since become the Locust Grove housing development off Route 225, near La Plata. A log and a rock used to bludgeon her were found by the body.

In preliminary hearings, Stiglitz said FBI analysts determined that a brown fiber found on the front seat of Mitchell's car came from a wig.

Testimony will be offered that the defendant at times wore a brown wig, Stiglitz said. In addition, he said, a witness will testify she saw Thomas with Mitchell's car after the slaying.

Buchheister in a pretrial filing said he would seek to demonstrate that another witness saw another person driving the car after the slaying. He also intends to tell jurors that DNA tests excluded Thomas as the source of bloodstains on Mitchell's jeans.

"They've done every scientific test in the world, and nothing has come back to my guy. That's what I intend to tell the jury," Buchheister said in an interview. "They've had four years to link up something scientific to my client, and they have nothing."

Stiglitz said the prosecution was not dependent on the DNA tests.

"The logical inference is it's the victim's blood -- which we knew," Stiglitz said.

In an earlier hearing, Clark ruled that Buchheister may not present evidence suggesting Mitchell was slain by members of a fraud ring dominated by Nigerians.

Federal prosecutors determined that Mitchell opened an account that channeled funds the ring obtained from using stolen credit card numbers. Authorities were planning to seek a search warrant for her apartment when she was killed.

However, after two lengthy U.S. District Court trials involving ring members, federal prosecutors do not believe those involved in the fraud killed Mitchell, Assistant U.S. Attorney Barbara Sale said.

"There was frankly no link that we could find," Sale said in a telephone interview.

She said police found electronic organizers, balance sheets and other evidence outlining illicit finances in Mitchell's apartment after her slaying, suggesting the homicide was not carried out to conceal evidence of the fraud ring.

CAPTION: BEVERLY R. MITCHELL