An FBI forensic expert testified Saturday in Casey Anthony's murder trial that a hair removed from the woman's car showed signs consistent with hair from a dead body.

Anthony is charged with first-degree murder in the death of her 2-year-old daughter, Caylee.

The single, 9-inch strand of light brown hair was the only hair of several collected by investigators to show signs of decomposition, Karen Korsberg Lowe told jurors.

Lowe, who specializes in microscopic hair examinations, described a dark banding seen on hairs from people known to be dead. She said the hair sample she examined showed this banding.

"It has a darkened band at the root portion of the hair. This is consistent with apparent decomposition," Lowe said.

The hair was similar to one pulled from Caylee's hair brush and was not similar to a hair sample from Anthony, she said.

Before Lowe took the stand Saturday, Anthony's attorney, Jose Baez, challenged her qualifications and tried to block her testimony.

Under cross-examination from Baez, Lowe said it was not unusual to find hairs in cars, as the average person loses 100 head hairs a day, and people can transfer hairs to other people.

"I couldn't say how the hair got there," Lowe said. "It's consistent with transfer or contact of some sort, but I don't know from whom."

When questioned again by prosecutor Jeff Ashton, Lowe said the hair showed characteristics of one that had been forcibly pulled.

Lowe was the first of two witnesses called Saturday.

Mike Vincent, an assistant supervisor with the Orange County Sheriff's Office crime scene unit, explained how he collected air samples and a stain from Anthony's car in 2008.

Another crime scene investigator testified Friday that he smelled the odor of human composition when he first opened the door to examine Anthony's car days after her initial arrest in July 2008. Caylee's skeletal remains were found in a wooded area near her grandparents' Orlando home in December 2008.

Anthony, 25, faces the death penalty if convicted.

Prosecutors say Caylee suffocated after duct tape was placed over her mouth. They contend that Caylee's decomposing remains were at some point in the trunk of Anthony's car.

Anthony's attorney says that the child accidentally drowned in the family's pool, and that Anthony's father, George Anthony, disposed of her body. George Anthony has denied that allegation.

Testimony will continue Monday.