CHATTANOOGA, Tenn. (AP) _ A form of DNA testing used to identify the remains of American soldiers and Russian Czar Nicholas II was introduced as evidence in a murder trial for the first time in a U.S. court.

Paul Ware, 27, went on trial last week for the rape and murder of a 4-year-old girl. Physical evidence included hairs found on the victim's body that were matched to Ware using mitochondrial DNA.

Unlike regular DNA fingerprinting, which comes from a cell's nucleus, mitochondrial DNA can be found in hair, bones or teeth. The evidence is believed to be more reliable and less vulnerable to contamination.

``This is really the first test in an U.S. criminal case,'' said Doug Deedrick, an FBI crime lab agent who gave DNA testimony for prosecutors in the O.J. Simpson trial. ``Now, the door is open. It will be accepted as a technology and validate it as a tool to help solve crimes.''

The FBI has been working on mitochondrial DNA testing since 1990. Deedrick said the Ware case was the first the FBI accepted since establishing the technology at its lab in June.

Tim Kupferschmid, senior DNA analyst for the Armed Forces Institute of Pathology, used the technology to identify the bones of Russian Czar Nicholas II last year and for the ongoing identification of the remains of soldiers who were missing in action, some of which date back to World War II.

``Scientifically, I don't think it's significant that (mitochondrial DNA) was introduced in a criminal case, but it does reinforce its validity,'' said Kupferschmid, who along with Deedrick monitored testimony about the evidence Wednesday.

But William Shields, a DNA expert from Syracuse, N.Y., said more validation studies are needed on mitochondrial DNA before it is considered a reliable investigative tool.

``Unfortunately, they are rushing it into a criminal case before it's ready,'' he said. ``There's no statistical weight for it.''

Ware was found drunk and nude on a utility room floor with the body of Lindsey Green on Oct. 1, 1994. An autopsy showed the girl suffocated as the result of too much weight on her 30-pound frame. She was raped and sodomized.

Red pubic hairs found on the victim's body were matched to Ware, who frequently stayed at the home where Lindsey was sleeping that night.

The defense contends baby sitter Paul Crum, the only other adult home that night, is the true culprit.

If convicted, Ware faces the death penalty.