Prosecutors on Tuesday presented their first piece of physical evidence in Scott Peterson's (search) murder trial -- a single strand of dark hair found on a pair of pliers and believed to be from his pregnant wife.

Detective Henry Hendee testified that he noticed the hair while collecting items from the warehouse where Peterson stored a 14-foot boat.

During Peterson's preliminary hearing, experts testified that DNA analysis indicated the hair likely came from Laci Peterson (search), but the defense has not conceded that point.

Prosecutors say Peterson killed his wife in their Modesto home around Dec. 24, 2002, trucked the body to San Francisco Bay (search) in a large tool box and dropped it overboard from the boat.

Defense lawyers maintain someone else abducted Laci Peterson, killed her and framed her husband.

Peterson, 31, could face the death penalty if convicted.

Prosecutors claim Laci Peterson never knew about the boat and that her husband bought it weeks earlier for the sole purpose of disposing of her body.

Peterson insisted he told his wife about it, and a witness told police Laci Peterson visited the warehouse after the boat had been purchased. The defense contends that could explain how the hair got on the boat.

Hendee also said he found suspected blood samples inside Peterson's truck. But it was not immediately disclosed in court whether the substance was, in fact, blood.

According to earlier testimony, Peterson told relatives that he had cut his hand and that police would probably find blood in the truck.

Hendee told jurors he collected samples near the driver's door handle and on the steering wheel.

Hendee said he also collected as evidence a hammer and cement chunks from the back of Peterson's truck. Prosecutors allege Peterson used homemade cement anchors to weight his wife's body.

Hendee testified he was assigned to search the nursery in the Petersons' home, finding two pairs of black maternity pants in a bag that raised his suspicions. He did not elaborate.

Peterson told authorities his wife was wearing black maternity pants when he left to go fishing the day he said he last saw her.

Later, prosecutors questioned Hendee about powdery residue found in Peterson's warehouse, indicating that Peterson made five cement anchors weighing 5 to 10 pounds each. Authorities, though, recovered only one.

Prosecutors showed the jury photographs of a flatbed trailer covered with patchy white residue and indicated there were five bare circles in the dust where Peterson allegedly made the anchors.

In other testimony Tuesday, an evidence technician who examined Scott Peterson after his wife vanished said he found no scratches or bruises or anything else to indicate there had been a struggle.

Doug Lovell of the Modesto Police Department testified that the examination took place as police became increasingly suspicious Peterson was responsible for Laci Peterson's disappearance.

"Did you notice any scratches or marks or anything on his body?" asked defense lawyer Mark Geragos (search).

"No, I didn't," Lovell replied.

The examination was done more than a week after Laci Peterson was reported missing on Dec. 24, 2002.

Prosecutors at Peterson's murder trial first called Lovell to testify about video and pictures taken of Peterson's home to show how meticulously authorities documented the suspected crime scene.

But in yet another example of how defense lawyers have tried to score points using prosecution witnesses, Lovell bolstered Geragos' claim that scant evidence implicates Peterson.