Lawyers representing Scott Peterson (search), the Modesto fertilizer salesman accused of killing his wife and unborn child, have asked a judge to exclude evidence, alleging two detectives mishandled the items.

Peterson's attorneys want the judge to keep strands of hair and other pieces of evidence out of the double murder case, according to documents filed late Monday at Stanislaus County Superior Court.

DNA tests have shown that the hair may belong to Peterson's slain wife, Laci, a source told The Modesto Bee before a sweeping gag order was imposed in the case.

The defense also is seeking to exclude testimony from a hypnotized neighbor and evidence from tracker dogs and tracking devices hidden in vehicles Peterson owned, rented or borrowed from family members, according to the defense documents.

Laci Peterson (search) was almost eight months pregnant when she was reported missing Christmas Eve. Her badly decomposed body was found in April along the shore of San Francisco Bay (search). The body of her unborn son was discovered just over a mile away.

Scott Peterson has pleaded innocent to two counts of murder in the deaths. A preliminary hearing is scheduled for Oct. 20.

Police found a single hair in a pair of pliers at the bottom of Peterson's boat during a Dec. 27 search, according to the defense documents.

The pliers were photographed with "one hair and a specific numbered placard in the picture." Multiple police reports refer to a single hair being found, the defense contends.

Detectives Al Brocchini and Dodge Hendee "spontaneously decided to review" the hair Feb. 12, defense attorney Mark Geragos wrote in the documents.

"These two Modesto Police officers supposedly found a second strand of hair while reviewing the evidence alone and without any supervision by a criminalist or lab technician," Geragos wrote.

The two hairs were submitted to a state Department of Justice crime lab the next day along with two of Laci Peterson's hairbrushes, according to the documents.

The defense contends that the DNA tests used are unreliable and that the detectives broke "the chain of custody" when they examined the items alone.

Geragos also contends that all tracking evidence is unreliable and should be excluded.