How Crime Scene Investigation Works

by Julia Layton

Examining the scene
There are several search patterns available for a CSI to choose from to assure complete coverage and the most efficient use of resources. These patterns may include:

• The inward spiral search: The CSI starts at the perimeter of the scene and works toward the center. Spiral patterns are a good method to use when there is only one CSI at the scene.
  
• The outward spiral search: The CSI starts at the center of scene (or at the body) and works outward.
  
• The parallel search: All of the members of the CSI team form a line. They walk in a straight line, at the same speed, from one end of crime scene to the other.
  
• The grid search: A grid search is simply two parallel searches, offset by 90 degrees, performed one after the other.
  
• The zone search: In a zone search, the CSI in charge divides the crime scene into sectors, and each team member takes one sector. Team members may then switch sectors and search again to ensure complete coverage.
  

Consider This Crime scenes are three dimensional. CSIs should remember to look up. If a CSI shines a flashlight on the ground at various angles, even when there's plenty of lighting, he'll create new shadows that could reveal evidence. It's easy to recover DNA from cigarette butts.

While searching the scene, a CSI is looking for details including:

• Are the doors and windows locked or unlocked? Open or shut? Are there signs of forced entry, such as tool marks or broken locks?
• Is the house in good order? If not, does it look like there was a struggle or was the victim just messy?
• Is there mail lying around? Has it been opened?
• Is the kitchen in good order? Is there any partially eaten food? Is the table set? If so, for how many people?
• Are there signs of a party, such as empty glasses or bottles or full ashtrays?
• If there are full ashtrays, what brands of cigarettes are present? Are there any lipstick or teeth marks on the butts?
• Is there anything that seems out of place? A glass with lipstick marks in a man's apartment, or the toilet seat up in a woman's apartment? Is there a couch blocking a doorway?
• Is there trash in the trash cans? Is there anything out of the ordinary in the trash? Is the trash in the right chronological order according to dates on mail and other papers? If not, someone might have been looking for something in the victim's trash.
• Do the clocks show the right time?
• Are the bathroom towels wet? Are the bathroom towels missing? Are there any signs of a cleanup?
• If the crime is a shooting, how many shots were fired? The CSI will try to locate the gun, each bullet, each shell casing and each bullet hole.
• If the crime is a stabbing, is a knife obviously missing from victim's kitchen? If so, the crime may not have been premeditated.
• Are there any shoe prints on tile, wood or linoleum floors or in the area immediately outside the building?
• Are there any tire marks in the driveway or in the area around the building?
• Is there any blood splatter on floors, walls or ceilings?

­The actual collection of physical evidence is a slow process. Each time the CSI collects an item, he must immediately preserve it, tag it and log it for the crime scene record. Different types of evidence may be collected either at the scene or in lab depending on conditions and resources. Mr. Clayton, for instance, never develops latent fingerprints at the scene. He always sends fingerprints to the lab for development in a controlled environment. In the next section, we'll talk about collection methods for specific types of evidence.


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"That's not the way they do it on television!"

" 'CSI' Effect" Is Mixed Blessing for Real Crime Labs according to Stefan Lovgren for National Geographic News


While the cool technology in the CSI crime lab sometimes seems lifted out of Star Trek, real-world experts say the equipment used on the shows is firmly rooted in reality.

"The gadgetry that you see on TV is very close to what we have in real life," said Dean Gialamas, the director of the forensics laboratory at the Orange County Sheriff-Coroner Department in Santa Ana, California. "The major difference is the application of some of that technology."

For example, on CSI, a computer automatically matches fingerprints to those in its database. But in real life, scientists must perform such detailed work. And while DNA testing on the show is instant, in real life it takes at least a week.

There have been some obvious errors. In one episode during the first CSI season, scientists put a casting material into a stab wound and let it harden. When they pulled it out, the cast was in the shape of a knife.

"That's totally unrealistic," Gialamas said.

Real-life investigations, of course, take a lot longer than they do on television.

"We don't show any of the immense amount of documentation that has to be done in the field," said Devine, the CSI producer. "Nobody wants to see someone sitting at their desk taking notes."

Real-life forensic scientists are also often too busy to focus on a single case.

Take, for example, the L.A. County Sheriff's Office, the largest sheriff's office in the United States. It handles more than 50,000 cases involving forensic evidence per year. A crime lab in Downey, south of Los Angeles, handles about 70 percent of the cases—those involving narcotics and alcohol.

The rest of the cases, including major crimes such as homicide and rape, are handled in a nondescript building on the edge of downtown Los Angeles. Here, scientists analyze a wide array of forensic evidence, from firearms and explosives to fingerprints, hair, and fiber.

The workload is so severe that forensic scientists may work two dozen cases at the same time, though there are exceptions. Two scientists spent two years solely on the case of Richard Ramirez, also known as the Nightstalker, a serial killer who stabbed, shot, raped, and tortured dozens of victims in southern California in the mid-1980s.

But improved technology, such as DNA testing and advanced databases, has helped scientists in their crime-solving quest. Forensic experts from the L.A. County Sheriff's Office recently solved a 20-year-old homicide by identifying the DNA in a piece of hair.

Real Life CSI: Crime Autopsy