FRANKLIN - DNA found on the clothing and body of an 11-year-old Girl Scout matches one of the two men on trial for raping and killing the Oil City girl in 1992, an FBI scientist told jurors.

FBI forensic examiner Jennifer Luttman testified over the weekend the chances were one in a quadrillion - that is a one followed by 15 zeros - that the semen found on Shauna Howe was not James O'Brien's.

O'Brien, 33, and his brother, Timothy O'Brien, 39, both of Oil City, are being tried on charges they murdered Shauna sometime after their friend, Eldred "Ted" Walker, snatched her off an Oil City street on Oct. 27, 1992, as she walked home from a Girl Scout Halloween party. Her body was found three days later under an abandoned railroad trestle.

Walker pleaded guilty last month to third-degree murder and kidnapping and agreed to testify against the brothers, saying he wanted the girl's family to "have peace."

Luttman, one of four FBI scientists to testify for the prosecution, told the jury that James O'Brien is the source of the semen found on Shauna's body and Halloween costume. Experts said a hair fragment on her shirt also came from him.

None of Shauna's clothes tested positive for semen at the time she was killed, but technology has progressed since then and the substance was later identified, state police said.

Also, tests of the four oral swabs state police had not analyzed in 1992 revealed the presence of semen on three of them, Luttman said. A DNA profile of an unidentified male was obtained from those three swabs and five stains on the girl's gymnast costume.

The profile wasn't matched to any suspect until investigators sent technicians a sample of James O'Brien's saliva in January 2002, Luttman testified. The DNA did not match either Timothy O'Brien or Walker, she said.

Attorneys for the O'Briens insist their clients didn't play a role in Shauna's death, suggesting that Walker is a liar who killed and raped the girl himself.