Crime Scene Investigation, Part 2
Blood is not immediately connected to crimes. The killing could have been an accident; the blood could be fake. Fortunately, advanced forensic equipment has enabled scientists and investigators to test blood to see if it is real or not. Samples are taken and blood drops are measured and the measurements are recorded. When blood droplets fall onto a surface, they form circle-shaped spatters and move slowly. Tiny blood drops come from high-speed impact, like when a gun is shot and blood spatters out fast. Forensic scientists follow blood trails to determine how the events of the crime played out. As mentioned before, criminals will do anything to get rid of bodies and evidence; that includes dumping bodies where they are least likely to be found. Fortunately, something can be done to find missing people who are presumed dead other than searching for their bodies -or remains of them-or having some poor traveler stumble on them. Bodies decompose and feed area plant life; crime botanists can look for vegetation that has recently changed. Crime victims who were attacked might remember what the weather was like at the time of the crime-for example, whether it was raining or snowing. The police can ask a meteorologist in the area when it started snowing or raining and then roughly determine when the crime occurred. Everyone is familiar with how cars are used in crimes n crimes-criminals hauling bodies away in vehicles, bank robbers making their getaway in cars. Information concerning these vehicles is vital. Witnesses and victims might be able to remember the car’s model and maybe figure out the year of its making and what it looked like. A recorded license plate number is also useful to investigators. Paint or tire tracks at the scene of the crime can give information on the kind of car that was driven there, and maybe help show if the vehicle was really there at the time the crime happened or not. ‘Impression prints’ are tire tracks left in soft substances, like mud or snow, and ‘contamination prints’ are made when a car drives on pavement after driving through something dirty, like oil or blood, that would easily leave marks. The way tire prints wear on the ground and unique marks on the tires can help investigators track the vehicles. Spare parts can accidently be left at crime scenes by criminals that help police officers make arrests. Also, cars missing license plates often cause suspicion, and more than one parking ticket has led to the arrest of a convicted criminal. Guns, when shot, spray a special powder called gunshot residue powder, which can be lifted off a suspect with tape. If chemicals known as antimony, lead, and barium can be found, they can lead to his conviction. Blowback, soft particles of matter sucked into a gun when it is shot, can also help investigators find criminals. Glass isn’t all the same-different objects are made out of different kinds of glass. Some events of a crime can be determined by seeing in which direction the glass broke-it always goes toward the person who broke it. A piece of glass can be tested by bending rays of light through it. Then the shard can be matched to a glass pane, cup, etc., that has light bend through it in the same way that the shard does. Glass shards found on suspects can be matched with broken objects or the same kind of glass shards found at crime scenes or near it. Another important clue used to find and convict criminals is fibers from clothing, blankets, etc. A special compound microscope with a unique mix of lenses can be used to look at fibers microscopically. This can help investigators make an arrest from a group of witnesses/suspects or find a criminal because fibers from carpets or bedspreads, especially a unique kind of carpet or blanket, can be matched to a manufacturer/store and lead to a suspect’s arrest. Even criminals can unintentionally give information to investigators. Sometimes, a criminal will grab a camera and start snapping pictures at or near the crime scene. If the camera is found, this can help investigators trying to solve a crime. Criminals will even make phone calls from a crime scene, and when this is discovered, the calls can be traced and lead to the arrest of that criminal. Many criminals also have the tendency to leave their marks at crime scenes; these are called modus operandi-or method of operating- by police, and they show the criminal’s ways of committing crimes, tools he uses, or something he leaves behind to show that he was there. For example, if a murderer leaves a piece of paper with a mark on it that investigators recognize at the scene of every murder he commits, that could be called a signature style. Even a dead victim can help solve a crime. Even if the body of a victim has decomposed by the time it is found, the skeleton can be used to determine other things about the victim, including the rough time period when the person was killed. When a skeleton or parts of a skeleton are found, investigators don’t naturally assume it was the body of a murder victim that decomposed. Using special equipment, they first determine whether it is the skeleton of a human or an animal. If it is a human, the bones can be further examined to figure out the gender of the victim, about how old he/she was when they died, his size and shape, what racial background he came from, what he did for a living, whether he was left or right handed, whether or not he died a violent death, and whether or not he had been injured at any point in his life. When a skull is the only bone that is found, a special artist can recreate with clay what he think the victim looked like when he/she was alive, using information such as the thickness at certain parts of the skull. Teeth can also be used to identify a victim, because their dental records can be found and matched to them, because every person has different teeth! If investigators think they have figured out who the person is, a picture of the victim can be found and the head in the picture can be matched to the skull. Autopsies are also very useful for figuring out how someone died. The contents of the victim’s stomach, when analyzed, tell what the food last eaten by the victim was and about how long ago it was eaten. Workers at a nearby restaurant may recall the victim buying the food and being with or followed by a certain person, who may turn out to be the criminal. By studying a body’s decomposition, the rough time period that the victim died/was killed in is determined. The time of death is determined by how heavily clothed the person is, if the victim is buried and how deep, and what weather he/she was killed in. Pictures of victims, before their death, and suspects are crucial. They help in determining events surrounding the crime and might help the investigators figure out who the criminal is. People who have gone missing around that time are suspected to have been involved with the crime.