A case that shows the disadvantage of the Locard’s exchange principle would be David Butler he was charged with murder he was a partial DNA match that was found underneath the victim’s fingernails. He didn’t commit the crime, as the victim has previously ridden in his taxi and has a skin condition causing him to shred skin, this led to him being acquitted of the crime. This case not only shows the disadvantages of the Locard’s exchange principle but shows how every contact does leave a trace when connected to the right person.
Associative evidence
Associative evidence links people to the place of the crime this helps the investigator gain an understanding of what actions had taken place. Blood spatter pattern, bullet paths and shoes prints can help find out what actual happened when the crime was committed.
While investigating a crime they may collect know substances called control samples. Items such as fibres from the carpet or glass fragments or even soil this can help prove the linkage of the suspect. This can link to a suspect if any of the items found from a crime scene is in a person’s car or on their clothing.
Associative evidence can have a negative effect as proving that there is evidence that can link to the suspect at the crime scene if it cannot then someone else had committed the crime. Another negative to this is that someone can be wrongfully committed for the crime as someone passing a person on the street can pass the evidence onto someone else.
The Barry George case helps show that you can pass any associative evidence to another person. Barry was arrested for the murder of Jill Dando due to the police finding a single gunshot residue on his jacket pocket. The conviction against him later dropped because they did not mention that armed police had arrested him and argued this was the reason as to why the gunshot residue was on Barry.
Importance of Preserving a Crime Scene
The first responder to a crime scene is usually a police officer in which they must properly protect and preserve a crime scene and wait for the other personnel to arrive. When evidence cannot be preserved physically then it should be documented and photographed if possible.
There are five major components for crime scene investigation:
Teamwork guarantees that bias does get included with the investigation and that justice is provided to the victim
This is an important part of evidence collection as detailed notes are taken. This is because most crime scenes are not permanent and is important to take note of what happened on the scene
The collecting of evidence is depended on the preservation of the crime scene at once on arrival
This is essential when analysing a crime scene
The investigator on the crime scene can adjust to new evidence or possibilities
To preserve a crime scene, they must block of the scene of crime by keeping track of who enters and exits making sure they evidence is always kept safe. There are disadvantages of not properly blocking of crime scene for example the destruction of the evidence, loosing or contamination of evidence, someone messing with the evidence. This important to avoid as if the evidence is vital in an investigation, if you do not block the crime scene properly then it would be inadmissible in court and couldn’t be used as evidence. Taking photographs on a crime scene is a disadvantage as they are using technology that can potentially crash or brake and could lose vital evidence for a case.
The Amanda Knox case shows why it is important to preserve a crime scene. While collecting evidence the detectives in this case wore shoe covers outside of the house while others did not have any protective clothing on inside the house. The evidence collected was unreliable and couldn’t be used as evidence in court.
Types of Evidence
Physical evidence can be an object or material relevant to the crime that has been committed. Examples of physical evidence include firearms, fingerprints, footprints, tool marks, hair and paint. Physical evidence can help lead back to the person that has committed the crime.
Non-physical evidence isn’t physically evidence but can be used to help an investigation. For example, witness statements, testimonies and eyewitnesses. The non-physical evidence can help prove that the suspect committed the crime.
The use of evidence can help a case when being investigated an example of this would be Colette Aram using DNA evidence collected from the crime scene helped convict the person that had murdered Colette. This can show that all evidence can lead back to the criminal.
Why and When a Crime Scene is Investigated
The goal of a crime scene investigation is to figure out what happen when the crime was committed and find the individual or individuals that committed the crime. A crime may have many separate locations for example the body may be found in one location but not killed in that location resulting in the body being moved. The scene where the body is found is usually called the primary scene. The main aims of a crime scene investigation are to decide a sequence of events of what happened and how the crime was committed, recover physical evidence of the crime and undercover a motive. A crime scene is usually investigated as soon as possible to make sure that the evidence can be used and not get contaminated but make sure that justice can be served for the victim of the crime.
Conclusion
While on a crime scene investigating the crime and analysing the evidence there are many positives when doing this for example finding the person that committed the crime and getting justice for the victim. All principles play a vital part in a criminal investigation and can help solve a case. However, there are disadvantages for every principle on a crime scene that can lead to contamination and false imprisonment if certain investigative techniques are done properly or are not collected properly this can have a negative impact on the cases development.
Issues of practice included here.
Surnames with capital letters.