By Mark A. Ober
Juror expectations have risen dramatically with the popularity of forensic evidence television programming. In certain cases, the courtroom does not disappoint. The field of forensic science is rapidly expanding and innovative. Although it remains true that nothing beats good detective work, investigators today routinely turn to science when catching criminals. Forensic investigation is the art of discovering hidden clues left by a perpetrator. Although sophisticated criminals sanitize the crime scene, evidence often remains, and clues can be gleaned through the examination of blood spatter, materials analysis, and the use of advanced equipment such as laser beams.
Long before the terms “forensic evidence” and “crime scene investigator” were coined, detectives had discovered the evidentiary value of fingerprints. No two people, not even identical twins, have the same fingerprint. It is also impossible to change a fingerprint. The FBI established a national repository for fingerprint records in 1924, filing prints lifted from crime scenes according to major pattern. At the time, law enforcement could obtain only patent prints, those visible to the naked eye. A criminal can easily remove patent prints. Latent fingerprints are not readily observable and can be easily missed, but they remain behind to identify, and perhaps to convict, the perpetrator. Today, these prints are discovered with the use of electronic, chemical, and physical processing techniques that permit the visualization of invisible latent prints.
In homicide cases, prime forensic evidence is gained during an autopsy. The corpse itself is a crime scene yielding critical evidence. The autopsy may reveal the entry and exit wound of a penetrating weapon, which can be crucial evidence in supporting or rebutting a claim of self-defense. The presence of defensive wounds on a victim’s body is useful in establishing a defendant as the aggressor. Pathologists examine bodily organs and fluids to yield evidence of poisoning, drug ingestion, or malnourishment.
When the crime scene is saturated with blood, a serologist may be able to scientifically reconstruct the crime. Blood is subject to gravity, and the pattern of the blood left behind can be of great evidentiary value. The final resting place of the homicide victim may not be the location where he or she was attacked. By identifying the location of the initial attack, investigators can search this area for additional clues. This location may yield additional biological evidence necessary to establish the identification of the killer, as well as non-biological evidence such as shoe prints or weapons. When multiple stab wounds have been inflicted to the same bodily area, it is difficult to determine the precise number of stab wounds. Each time a weapon is drawn back, blood flies from the weapon, leaving a cast-off stain. A serologist will study the pattern of cast-off stains to help determine the number of strikes. This evidence may be critical in proving premeditation or self-defense.
These forensic tools are often an important part of a successful prosecution. Our office will continue to use these methods to seek justice in the courtroom.
