Topic 1.3 - Explain how evidence is processed (6 marks, 30 mins)
Types of evidence
Physical evidence
Any tangible evidence from a crime scene could be considered physical evidence, for example: fingerprints, bullets, blood samples, fibre evidence. It’s an
important aspect of criminal investigations and so great care must be taken to avoid contamination to ensure it is admissible in court.
Testimonial Evidence
Evidence which is in the form of a written or spoken statement. Can support either the prosecution or defence. Written statements have to be disclosed
to either side so they can prepare for court. Must be admissible, must comply with the rules of evidence. Police will take statements at the crime scene,
and the media can be used to help witnesses come forward. Evidence is given in the witness box and the opposing side has a chance to question it.
Defendants cannot be forced to give evidence and vulnerable witnesses may give evidence by video link.
Physical evidence
Locard’s Exchange Principle - ‘Every contact leaves a trace’. Materials from the crime scene will be present on the offender.
Collecting, transferring and storing physical evidence
Bodily fluids and tissues
Bodily fluids can provide important identification evidence as DNA can be extracted and compared with control samples from suspects.
Blood - The blood should first be allowed to air dry, and if any fabric has blood on it. Once blood has been collected by CSI it’s packaged and sent to the
laboratory for analysis by forensic scientists within 24 hours. Blood can be traced even if it's soaked through carpet. Need to be careful to not
contaminate stains with each other. Sian Roberts' case, she was stabbed to death in her home. The murderer was identified due to the bloody footprints
that were found on the floor in Robert's home.
Semen - Found on clothing or bedding by CSI. Needs to be air dried before it’s sent off for analysis. Once it’s dry, it should be placed in a paper bag,
sealed inside a polythene bag, and then sealed again and labelled and then sent to the laboratory for forensic scientists to analyse.. A polythene bag is
used to ensure no contamination takes place, and so it is also important that everything is bagged separately.
Saliva - From bites on the victim, can be swabbed to provide samples for DNA analysis. Ted Bundy was caught from the DNA from bite marks he left on
his victims and a cast could be made from it. Bite marks are photographed by CSI and sent to the laboratory for forensic scientists to analyse.
Types of evidence
Physical evidence
Any tangible evidence from a crime scene could be considered physical evidence, for example: fingerprints, bullets, blood samples, fibre evidence. It’s an
important aspect of criminal investigations and so great care must be taken to avoid contamination to ensure it is admissible in court.
Testimonial Evidence
Evidence which is in the form of a written or spoken statement. Can support either the prosecution or defence. Written statements have to be disclosed
to either side so they can prepare for court. Must be admissible, must comply with the rules of evidence. Police will take statements at the crime scene,
and the media can be used to help witnesses come forward. Evidence is given in the witness box and the opposing side has a chance to question it.
Defendants cannot be forced to give evidence and vulnerable witnesses may give evidence by video link.
Physical evidence
Locard’s Exchange Principle - ‘Every contact leaves a trace’. Materials from the crime scene will be present on the offender.
Collecting, transferring and storing physical evidence
Bodily fluids and tissues
Bodily fluids can provide important identification evidence as DNA can be extracted and compared with control samples from suspects.
Blood - The blood should first be allowed to air dry, and if any fabric has blood on it. Once blood has been collected by CSI it’s packaged and sent to the
laboratory for analysis by forensic scientists within 24 hours. Blood can be traced even if it's soaked through carpet. Need to be careful to not
contaminate stains with each other. Sian Roberts' case, she was stabbed to death in her home. The murderer was identified due to the bloody footprints
that were found on the floor in Robert's home.
Semen - Found on clothing or bedding by CSI. Needs to be air dried before it’s sent off for analysis. Once it’s dry, it should be placed in a paper bag,
sealed inside a polythene bag, and then sealed again and labelled and then sent to the laboratory for forensic scientists to analyse.. A polythene bag is
used to ensure no contamination takes place, and so it is also important that everything is bagged separately.
Saliva - From bites on the victim, can be swabbed to provide samples for DNA analysis. Ted Bundy was caught from the DNA from bite marks he left on
his victims and a cast could be made from it. Bite marks are photographed by CSI and sent to the laboratory for forensic scientists to analyse.
