Due to the demands of the crime laboratory, not all examiners actually go to the crime scene to collect evidence and carry out testing in the field. Those laboratories where examiners do serve the dual role of laboratory analyst and scene investigator typically limit the on-scene aspect to major cases. Otherwise, there simply would be no way to get all the requested work done back at the lab.
Big city police departments, such as the NYPD and the Washington Metropolitan Police Department, have special crime scene investigation units whose sole responsibility is to go to the scene and collect the evidence for the laboratory examiners. When there are special needs at the crime scene, firearms and fingerprint examiners may be called in even though this may not be part of their normal routine.
With regard to fingerprints it is usually the responsibility of the persons assigned to the crime scene units to locate, develop, and lift latent prints at crime scenes. The actual comparison of crime scene prints with suspects' prints will usually be done in the crime lab by the fingerprint examiner.
Crime scene investigators are also trained to collect bullets, cartridge cases, and other ammunition components for examination by firearms examiners. Firearms examiners can be called in when special needs arise. For example, a sniper shooting involving a shot fired from a long distance that needs special bullet trajectory analysis may require a firearms examiner to come to the scene. This was the case in the investigation of the Beltway Sniper (see sidebar).
Crime laboratories in less populated jurisdictions can typically allow their examiners to devote time to crime scene investigations, in addition to their laboratory duties. These laboratories usually do not have the lab caseload demands that their big city counterparts have.
In 2002 a sniper murdered a series of people who were refueling their vehicles at gas stations and convenience stores in the Washington, D.C., area, gripping area residents in fear for weeks. Members of the firearms identification unit of the Bureau of Alcohol, Tobacco and Firearms (ATF) came to the scenes of the various shootings in an effort to determine where the shots were fired from and to see if any other evidence could be found at the scenes.
The firearms analysts were able to conclude that a 223-caliber rifle was involved and that one weapon was responsible. They reached this conclusion by examining markings left on the bullets recovered from the victims. Once the weapon was recovered, it was positively identified using these same markings.
The "Beltway Sniper" was actually two men, John Muhammad and Lee Malvo, who fired a rifle from the trunk of their car. Malvo was implicated as a shooter through a fingerprint found on the weapon and a fingerprint found on a cartridge case near one of the scenes. Finding identifiable fingerprints on weapons and fired cartridge cases is pretty uncommon, making this a stroke of good luck for investigators. Muhammad and Malvo received the first of their convictions in 2004.
The Beltway Sniper Case
Small, local police agencies often call upon state and federal laboratories to send examiners to assist at crime scenes when the local agencies do not have their own examiners. Even larger agencies will call on Federal Bureau of Investigation (FBI) or Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) examiners to assist at crime scenes in high-profile cases. This is because the federal agencies sometimes have more resources and access to more specialized personnel and equipment than the state and local agencies do.
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