Collection and Preservation of Evidence
Bagging Evidence
Evidence retrieved from a crime scene must be correctly collected by the scenes of crime officer, this means the correct technique must be used and the correct bag according to the type of evidence it is. It is important that the scenes of crime officer abides by all procedures before collecting the evidence to limit the chance of contamination occurring, personnel protective equipment must be worn by the scenes of crime officer when handling any piece of evidence within the crime scene. Before bagging the pieces of evidence there is a set procedure that must be carried out, this is to photograph the piece of evidence. The photograph must consist of three things these being; the piece of evidence, an L shaped scale and an evidence card. It is important that an L shaped scale is included as this gives an investigator a rough estimate of the size of the piece of evidence that has been retrieved, it is also important that an evidence card is included as the evidence card consists of the details of the scenes of crime officer that collected the evidence, what the evidence is and where it was found. Evidence will be bagged after this procedure has been taken out, although the type of packaging will be dependent upon the evidence retrieved.
Biological Evidence - Depending on where the biological piece of evidence is found will depend on how it is packaged. If it is found of a surface it will either be swabbed or picked up with tweezers. Swabs will only be used on liquids found at the scene, the swab will then be sealed and placed into a plastic bag. Tweezers will only be used on hair samples found at a scene, the hair sample will be picked up and sealed in a plastic bag, where as if a fingerprint is present at a scene this will be lifted and placed onto a slide the slide will then be placed into a plastic bag.
Physical Evidence - Depending on whether a weapon has been found or clothing has been seized will depend on the packaging used. Weapons are placed in plastic tubes as this is the safest possible way to bag them, if a sharp weapon is placed in a plastic bag this may result in the bag being split and the piece of evidence being lost. All clothing that is seized from a crime scene will be placed in a large paper bag, this is to protect any evidence located on the clothing as if the packaging was change this may result in any biological or chemical evidence rubbing off.
Chemical Evidence - Chemical evidence is usually found in liquid form at a crime scene, depending on the SOCO they may decide to complete a spot test at the scene or bag the evidence and follow this procedure out in a forensic lab. If the evidence is bagged this will usually be picked up with a spatula and placed into a plastic tube, this will allow the forensic scientist to retrieve the sample from the tube quickly and effectively.
All evidence taken from the crime scene is effectively bagged to ensure it is kept safe until given to the forensic scientist also by effectively bagging the evidence in the correct packaging it allows the evidence to be preserved and not decomposed e.g. bodily fluids on clothing decompose or rub off if place into a plastic bag.
Biological Evidence - Depending on where the biological piece of evidence is found will depend on how it is packaged. If it is found of a surface it will either be swabbed or picked up with tweezers. Swabs will only be used on liquids found at the scene, the swab will then be sealed and placed into a plastic bag. Tweezers will only be used on hair samples found at a scene, the hair sample will be picked up and sealed in a plastic bag, where as if a fingerprint is present at a scene this will be lifted and placed onto a slide the slide will then be placed into a plastic bag.
Physical Evidence - Depending on whether a weapon has been found or clothing has been seized will depend on the packaging used. Weapons are placed in plastic tubes as this is the safest possible way to bag them, if a sharp weapon is placed in a plastic bag this may result in the bag being split and the piece of evidence being lost. All clothing that is seized from a crime scene will be placed in a large paper bag, this is to protect any evidence located on the clothing as if the packaging was change this may result in any biological or chemical evidence rubbing off.
Chemical Evidence - Chemical evidence is usually found in liquid form at a crime scene, depending on the SOCO they may decide to complete a spot test at the scene or bag the evidence and follow this procedure out in a forensic lab. If the evidence is bagged this will usually be picked up with a spatula and placed into a plastic tube, this will allow the forensic scientist to retrieve the sample from the tube quickly and effectively.
All evidence taken from the crime scene is effectively bagged to ensure it is kept safe until given to the forensic scientist also by effectively bagging the evidence in the correct packaging it allows the evidence to be preserved and not decomposed e.g. bodily fluids on clothing decompose or rub off if place into a plastic bag.
Sealing and Tagging Evidence
After bagging the piece of evidence the next procedure is to effectively close the bag and also place a tag on the selected bagging. The bag will be sealed with JLAR tape, this is strong effective tape that has to be cut open if access to the evidence is needed. By using JLAR tape to effectively secure the bag this will ensure the evidence is safe, as if the packaging has been opened this will be noticeable due to the JLAR tape being cut, the SOCO will also write over half of the bag and half of the tape with there name or initials this also makes the evidence more secure. If the evidence has been tampered with the forensic scientist will be able to identify this due to the letters not matching up correctly on the JLAR tape.
A tag is also placed on the evidence which is completed by the scenes of crime officer, this tag states the details of the scenes of crime officer, what the evidence is, where it was found, a reference number and also a case number. By filling out the tag correctly this ensures that the evidence wont be lost and if it was lost it was clear who the evidence belonged to and which crime it came from, this can result in the evidence being returned. The forensic scientist will also look at the details located on the tag to see if the evidence is beneficial within the case by evaluating its validity.
A tag is also placed on the evidence which is completed by the scenes of crime officer, this tag states the details of the scenes of crime officer, what the evidence is, where it was found, a reference number and also a case number. By filling out the tag correctly this ensures that the evidence wont be lost and if it was lost it was clear who the evidence belonged to and which crime it came from, this can result in the evidence being returned. The forensic scientist will also look at the details located on the tag to see if the evidence is beneficial within the case by evaluating its validity.
Collection and Preserving Evidence within the Soham Murders
All evidence retrieved from the crime scene, Ian Huntley's house and the small building outside of Soham Village College was correctly bagged and tagged. This was an advantage within the case as it ensured that no evidence was lost, tampered with or ruined, the bodies of both girls was sent to a pathologist for further examination to determine the cause of death and also the time of death. Forensic analysis was carried out correctly due to the evidence being preserved correctly throughout the investigation process, although the forensic scientists acted upon the evidence quickly due to it not being found until two weeks after the crime was committed.