CALIFORNIA ? A hair found in a pair of pliers on the boat Scott Peterson took fishing the day his wife disappeared matched a genetic sample from Laci Peterson’s mother, an FBI expert testified Wednesday, as prosecutors sought to have Scott Peterson tried in the slaying of his wife and unborn son.

For much of the day inside a packed Modesto courtroom, FBI lab supervisor Constance Fisher testified about the disputed method of DNA analysis she specializes in that can show a genetic match between a mother and child.

She testified that a 1-inch strand of hair found on pliers in the boat did not match Scott Peterson, but did match a swab of DNA taken from the mouth of Laci’s mother, Sharon Rocha.

Defense lawyer Mark Geragos challenged the admissibility of the testimony, saying the analysis was the focus of a “raging debate” in the scientific community and suggesting that the hair sample may have been contaminated or tampered with by law enforcement.