AC1.3
Physical evidence
Physical evidence is important within investigations as it gives the cases a form of scientific backup,
making it more reliable. This revolves around the Locards exchange principle which suggest that
every time someone enters and environment, they leave something behind as well as take
something from the scene. SOCOs and CPIs use this principle within their procedures as a way of
ensuring that all evidence is collected carefully, avoiding any contamination. One common type of
physical evidence are blood stains, and it is crucial that these are handled careful as they can play a
huge role when it comes to identifying the victim. If the stains are wet, they should be allowed to dry
at room temperature, preventing the wet blood from transferring onto other parts of the item once
folded during the transfer. This also preserves the pattern of the blood and majorly reduces risks of
contamination. Once the blood is successfully collected by the forensic scientists, the samples are
placed in a labelled container and sealed to avoid anything coming in contact with it. The timeframe
to transfer the blood from the crime scene to the lab is around 28 hours, the forensic scientists will
take over from there and swab the sample to extract any DNA from it. This will allow matches to be
made which helps the forensics identify who the blood belongs to therefore exposing the name of
the victim or offender. Another type of physical evidence is hair samples and fibre or threads. The
hair samples are typically found on clothing which are then packaged and sealed in paper bags (less
chance of any evidence degrading), and later submitted for lab examination. Once present at the lab,
the forensic scientists will extract DNA from the root of the hair revealing who the hair belongs to.
Fibres and threads are similarly likely to be found or caught onto clothing/other materials however
these are extracted using tweezers and gloves. The samples are wrapped in paper, placed in an
envelope and sealed with labels. By being packaged separately, the forensics are able to accurately
examine each sample and determine the type and colour of the fabric, even where it originates
from. A case study where physical evidence was crucial was Melanie Waldor (a woman killed by her
husband - Peter Waldor). The blood stains revealed on the mattress helped determine that Melanie
was in fact killed in her bed and her husband was lying.
Testimonial evidence
On the other hand, testimonial evidence contains the spoken words of witnesses whether it’s
eyewitnesses or fact/expert witnesses. Collection is usually done through interviews or recordings
which are taken prior the court case trial by the detectives. These are then written out and reviewed
(also signed) by the witnesses in order to confirm its truthfulness, before being transferred to the
court to be used in the trial. It is stored securely but still available to the personnel, specifically the
prosecution or the defendants' legal teams, involved in the investigation. The analysis measures how
alike the statements are and if they match, it is usually upto the CPS to check the evidence and make
sure it it credible prior to the trial. During the trial, hearsay evidence is more vulnerable to cross
contamination primarily due to examine its validity, the legal teams from both sides will question the
witnesses to examine whether their statements corroborate with the evidence. The significant
importance of the evidence needing to be analysed correctly could be seen in the case of Damilola
Taylor where 14-year-old girls lies were exposed during the trial, if they were not spotted, the
inaccurate testimony could’ve led to the conviction of an innocent person. The fact that the lies were
obvious resulted in criticism for the CPS for their carelessness and accusations of only a small
amount of time being spent on reviewing the evidence properly.
Physical evidence
Physical evidence is important within investigations as it gives the cases a form of scientific backup,
making it more reliable. This revolves around the Locards exchange principle which suggest that
every time someone enters and environment, they leave something behind as well as take
something from the scene. SOCOs and CPIs use this principle within their procedures as a way of
ensuring that all evidence is collected carefully, avoiding any contamination. One common type of
physical evidence are blood stains, and it is crucial that these are handled careful as they can play a
huge role when it comes to identifying the victim. If the stains are wet, they should be allowed to dry
at room temperature, preventing the wet blood from transferring onto other parts of the item once
folded during the transfer. This also preserves the pattern of the blood and majorly reduces risks of
contamination. Once the blood is successfully collected by the forensic scientists, the samples are
placed in a labelled container and sealed to avoid anything coming in contact with it. The timeframe
to transfer the blood from the crime scene to the lab is around 28 hours, the forensic scientists will
take over from there and swab the sample to extract any DNA from it. This will allow matches to be
made which helps the forensics identify who the blood belongs to therefore exposing the name of
the victim or offender. Another type of physical evidence is hair samples and fibre or threads. The
hair samples are typically found on clothing which are then packaged and sealed in paper bags (less
chance of any evidence degrading), and later submitted for lab examination. Once present at the lab,
the forensic scientists will extract DNA from the root of the hair revealing who the hair belongs to.
Fibres and threads are similarly likely to be found or caught onto clothing/other materials however
these are extracted using tweezers and gloves. The samples are wrapped in paper, placed in an
envelope and sealed with labels. By being packaged separately, the forensics are able to accurately
examine each sample and determine the type and colour of the fabric, even where it originates
from. A case study where physical evidence was crucial was Melanie Waldor (a woman killed by her
husband - Peter Waldor). The blood stains revealed on the mattress helped determine that Melanie
was in fact killed in her bed and her husband was lying.
Testimonial evidence
On the other hand, testimonial evidence contains the spoken words of witnesses whether it’s
eyewitnesses or fact/expert witnesses. Collection is usually done through interviews or recordings
which are taken prior the court case trial by the detectives. These are then written out and reviewed
(also signed) by the witnesses in order to confirm its truthfulness, before being transferred to the
court to be used in the trial. It is stored securely but still available to the personnel, specifically the
prosecution or the defendants' legal teams, involved in the investigation. The analysis measures how
alike the statements are and if they match, it is usually upto the CPS to check the evidence and make
sure it it credible prior to the trial. During the trial, hearsay evidence is more vulnerable to cross
contamination primarily due to examine its validity, the legal teams from both sides will question the
witnesses to examine whether their statements corroborate with the evidence. The significant
importance of the evidence needing to be analysed correctly could be seen in the case of Damilola
Taylor where 14-year-old girls lies were exposed during the trial, if they were not spotted, the
inaccurate testimony could’ve led to the conviction of an innocent person. The fact that the lies were
obvious resulted in criticism for the CPS for their carelessness and accusations of only a small
amount of time being spent on reviewing the evidence properly.
