# The Use of Math in Crime Scene Investigations

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Students seeking a career in crime-scene investigation must have a solid education not only in science, but also in mathematics. Crime-scene investigators use math to answer the questions raised at a crime scene. Math is used to determine how crimes are committed, when they were committed, and even who committed them.

## Patterns

When narrowing down suspects, investigators must examine fingerprints and DNA to create a list of genetic qualities present. DNA analysis is based on locating similar patterns from a human sample and samples located at the crime scene. This is a process by which more patterns create a more positive match in the investigation. Similarly, fingerprint identification is accomplished by measuring distance between grooves as well as the pattern of the prints, then comparing two samples to find points of similarity.

## Collecting Data

Crime-scene investigators gather data and then compare this information to existing databases to determine information such as the physical characteristics of a suspect. For example, when examining foot prints in dirt or mud, investigators are able to determine how much a suspect weighs by comparing the depth of the print to a list of constants. The length between foot prints can also be used to determine the height of the suspect. These calculations can be made by plotting the length of the gait or depth of a print onto a graph of known data, finding the variable using their known constants.

## Measurement

Part of crime-scene investigations involves determining when a death occurred. This time frame can be constructed by using measurements such as the temperature of the victim and the surrounding area. The longer a body remains in an area, the closer to the environment's temperature it becomes. Comparing this data can create an accurate time in which the crime occurred, ruling out suspects or incriminating others.

## Distance

Using the data collected on when a crime took place, crime-scene investigators are able to plug this information into an equation that can determine how far a suspect traveled to commit a crime, and how far from the crime scene the suspect could have gotten since committing the crime. This is accomplished by measuring the average speed of someone on foot, or in a vehicle, and comparing it to where the suspect was thought to be directly before or after the crime. Using time and distance, crime-scene investigators are able to create a radius in which the suspect could have traveled to and from.

## Trajectories

Whether it is bullet holes or blood splatters, crime-scene investigators are able to use mathematics to determine the trajectory of a falling object. Every object that is propelled through the air falls in an arc that can be measured to determine the speed and location from which the object began. This can be applied to crime-scene investigation by determining where a bullet was fired, or the height and force in which a wound was created based on how the blood splattered.

References
Writer

Dan Chruscinski has written pieces for both business and entertainment venues. His work has appeared in "Screen Magazine" as well as websites such as Starpulse.com. Chruscinski graduated in 2006 with a degree in English literature from Illinois State University.

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