Impression Evidence and its Impact on Investigation



What is Impression Evidence?

Impression evidence is a major contributor to move a crime scene investigation forward. Basically, it is a type of evidence wherein objects retain their characteristics or create an “impression” on other physical objects within a crime scene when it is stamped or pressed against each other. Because they are hardly noticeable unless closely examined, most impression evidences are overlooked during examination of a crime scene. Therefore, it is important for crime scene investigators to re-examine the site of a crime in order to verify other evidences that have been missed, especially impression evidence.

This type of evidence are categorized as two things: impressions made on either hard or soft surfaces. Moreover, there are two dimensional impressions wherein investigators can determine the width and length of the object that left an impression on a given surface. Meanwhile, there are also three dimensional impressions that add depth to the width and length measurement. Therefore, the latter type of impression evidence enable crime scene investigators to have a more precise idea of what type of object might have left that impression. 

Its Importance to Crime Scene Investigation

If you have witnessed crime scene investigations, whether actual or on TV, you should have noticed that investigators use objects such as microscope or magnifying glass during examination. These items are useful in recognizing impression evidence that are not normally visible with the naked eye, so assistance of these tools enable investigators to find more precise evidence.

Fingerprints are an example of impression evidence that is very useful in pointing to an identity of the person involved in a crime. Any form of print or impression gathered from the crime scene are examined for DNA profiling. These steps or prints left by a suspect on the crime scene are recognized as valid evidence in court and is used to testify the person's present at the scene when the crime was staged. 

Types of Impression Evidence

There are several types of impression evidence, but there are a few common ones that investigators search for at a crime scene. These provide valuable clues that will enable investigators to put together all events that might have transpired at a scene. Some impression evidence, if strong enough, could even point to a suspect's identity.

Fingerprints

Fingerprints are impressions left by a suspect at a crime scene when they touch objects or even the victim's body. Since fingerprints are not readily visible, investigators use specialized powder in order for the fingerprints to become visible during examination and analysis. Fingerprints have been honored at the court as a valid evidence that could solve the identity of a crime suspect.

Footprints

Identifying latent footprints are similar to developing latent fingerprints. They use the same technique and equipment for the procedure. Investigators look for such impression on tiled floors, chair bottoms, cabinets, or counter tops. Once such impressions are mechanically recovered, they use tapes to lift it off and slid into a plastic for later examination. Those impressions can be used for matching and identification.

Tool marks

This particular impression is typically found at areas of entry. They are used to identify what methods of force was used by the suspect to gain entrance into the crime scene, whether it is a house or apartment. 

Tire Tread

When suspects escape the crime scene riding a vehicle, crime scene investigators also use tire tread impressions left on the soil, mud, or any type of surface where the suspect drove towards. However, if the suspect drove through grass or carpet, the effect produced by the passing of the tire mostly rebounds and leaving not enough impression on the surface. But they can be vital evidence used in a crime scene investigation to point to which direction the suspect driver was headed to. 



