Body of Evidence

By Sora Song

All the high-tech gadgets and tests won't matter a bit if evidence isn't meticulously gathered at the scene of a crime. It's the little things that count-a stray hair, a piece of lint, a smudge of mud. This trail of tiny crumbs could ultimately lead straight to the killer

Clues at the scene

FINGERPRINTS Most prints, set down by oils and sweat on the surface of fingers and hands, are not easy to spot. But investigators have a hefty bag of tricks to expose them-powder, chemicals, lasers and lights. Or even plain old superglue. Prints that are invisible on things like duct tape will appear once subjected to fumes from the heated glue

FIBERS What looks to the eye like a bit of lint actually may be a forest of clues. Scientists microscopically comb samples for human and animal hair, clothing threads, carpeting and even plant material to identify everything there and perhaps place a suspect at the scene of the crime

BLOOD Using DNA, experts can identify whose blood was left at a crime scene. Investigators also pay careful attention to how the blood appears: patterns of smears, splatters or spray help re-create the movements of both the victim and the killer. The shapes of the drops can also indicate the height from which the blood fell

Which clues are real? It's not enough to "bag and tag" everything at a crime scene. The trick is to figure out what's important. If, for example, a wife is suspected of killing her husband in their bedroom, virtually all trace evidence in the room-fibers, hairs, fingerprints-could be useless. Proving that the wife was in her own room probably won't help the case

VOICE PRINTS Like DNA or fingerprints, voices are unique. Graphs measure the intricacies of a particular voice, obtained from threats or ransom demands made over the phone or extracted from surveillance tapes

HANDWRITING Similarly, no two people have the same handwriting. Investigators can compare evidence with handwriting samples from suspects. Using an infrared spectrometer, scientists can also identify specific ink types

FOOTPRINTS Shoe marks in anything from dust and dirt to blood or mud can be collected. To pick up a shoeprint in dust, experts use a sheet of electrified mylar that picks up dust like a big piece of Scotch tape. Soil tracked by an assailant could reveal where he has been or where he lives. Prints may also reveal the size, style and make of a shoe

BULLETS AND CARTRIDGES Every rifled gun barrel leaves unique marks on bullets and cartridges. By comparing two bullets, experts can determine whether they were fired from the same weapon

Clues on the body Often the most pivotal, if grisly, task is performed by the medical examiner. His job is to unravel the mystery behind three main questions:

CAUSE OF DEATH The medical examiner may study wounds to measure how deep a knife penetrated the body or examine the shape of a crushing blow to the head to determine what kind of bludgeon was used. Other evidence such as bullets or fibers can also be collected from the body, and the examiner may look for evidence of drugs, alcohol or poison

MANNER OF DEATH This always falls into one of four categories: suicide, homicide, natural or accidental. Often the manner is fairly apparent. Sometimes, though, a homicide may be disguised as a suicide, forcing investigators to probe deeper

TIME OF DEATH "You can't declare time of death, not with any accuracy," says Robert Gaensslen, head of forensic science at the University of Illinois in Chicago. But such indicators as body temperature and rigor mortis can help examiners estimate. Even the pattern of insects that arrive to feast on a rotting carcass can be helpful