Medical examiners use numerous tests to determine identity

By BETH FOUHY
Associated Press Writer

SAN FRANCISCO (AP) Forensic experts say that even badly decomposed human corpses, like those of a woman and an infant boy that washed up on a bayside park, still offer up numerous clues that can guide investigators in making a positive identification.

Examiners are trying to determine if the woman's body found Monday is that of missing Modesto resident Laci Peterson, the focus of a massive search since she was last seen on Christmas Eve. She was eight months pregnant at the time, due to give birth to a baby boy in February.

On Sunday, the body of an infant was discovered about a mile from where the woman's body was later found. Examiners are trying to determine if there is a link between the two.

Dr. Henry Lee, former director of the Connecticut State Police Forensic Science Laboratory and a noted criminologist who provided expert testimony in the O.J. Simpson murder trial, said examiners often do a series of initial anthropological measurements on skeletal remains, particularly bones, as a first step in making an identification.

``Even in water, bones will not shrink or expand,'' Lee said. ``They are constant.''

If the height of the skeleton is determined not to match the height of a missing person, Lee said that person can be eliminated.

Making a positive identification, as opposed to ruling someone out, is usually more difficult and time consuming. Experts said that analyzing dental records is the best way to identify a body that has decomposed, but that particular measurement may not be of help in this case. A Contra Costa County sheriff's deputy would not comment Tuesday on published reports that the woman's body came ashore missing its head and legs.

Fingerprints are also a key way to determine identity. Lee said that even after months in the water, if there is any remnant of skin on the victim's fingers a fingerprint can be reconstructed. An examiner would remove skin cells from the fingers and place them in a petri dish, adding glycerine to let them slowly rehydrate. Eventually, the print would be recreated.

If dental and fingerprint records can't be used, the next step would be to extract DNA from the body, usually from a dense bone such as the thigh bone. Examiners would then compare it to a DNA sample lifted from personal items.

``Things used by her and only by her,'' said Benny DelRe, director of the Santa Clara County Crime Lab. ``Her toothbrush, since it would have cell samples from her mouth. The razor she uses to shave her legs. A hairbrush that has some hair with root material attached. Any of those would be great reference items.''

If comparing the DNA sample to those items proved inconclusive, DelRe said investigators would probably seek a blood test from the victim's mother and father, to do a so-called paternity workup.

A paternity workup would also be the best way to determine whether the body of the infant came from the dead woman.

``You would take a DNA test from the fetus and compare it with her, and with Mr. Peterson, to determine paternity,'' said Lee.

(Copyright 2003 by The Associated Press. All Rights Reserved.)