Unit 2 – Science at work: Section 11.2

Blood typing can determine whether a blood stain is human and the blood group to which it belongs. Samples of DNA can be extracted from blood, semen and saliva. DNA can be cut up into fragments and separated by electrophoresis, and the DNA profile of the material from a crime scene can be matched with great certainty to the DNA provided by a suspect. This technique of DNA profiling can also be used to show whether or not people are related.

Candidates should be able to use data, theories and explanations to:

• draw conclusions from the results of blood tests and DNA profiling

Using databases Dental and medical records, vehicle records held on the DVLC database, insurance company records of valuable items, fingerprint and DNA databases and police records of descriptions of missing persons are examples of databases that are useful in forensic investigations. If a match can be found in a database this increases the probability of a positive identification and a mismatch may be equally important to eliminate a suspect from the police inquiry.