Three small stains on the back of 11-year-old Shauna Howe's leotard remained a mystery for years after her murder outside Oil City.

Those stains have since been determined to be semen, and they are expected to be at the center of testimony when the trial of Oil City brothers Timothy O'Brien, 39, and James O'Brien, 33, continues today in Venango County court.

The O'Briens are being tried on charges they murdered Shaunasometime after their friend, Eldred "Ted" Walker, snatched her off the streets of Oil City on Oct. 27, 1992 as she walked home from a Girl Scout Halloween party. Shauna had been dressed up as a gymnast.

State police have said DNA tests conducted at an FBI crime lab in 2002 found the semen matched a DNA sample taken from James O'Brien. None of Shauna's clothes tested positive for semen at the time she was murdered, but technology has progressed since then and the substance was later identified, state police said.

Yesterday, Mr. Walker testified about a questionnaire police gave him about the murder in 1996. Asked whether he knew anything about Shauna's murder, Mr. Walker said he didn't "know anything about them."

Erie County District Attorney Brad Foulk, who is assisting Venango County prosecutors, asked Mr. Walker who "them" was. "The O'Briens," he answered.

Mr. Walker has already pleaded guilty to third-degree murder and was sentenced to 20 to 40 years in Shauna's death.