Sources for section 3
Discuss a past, a present and a future technique, their advantages and disadvantages.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3831584/

https://www.promega.com/~/media/files/resources/conference%20proceedings/ishi%2010/oral%20presentations/01crow.pdf?la=en

http://aboutforensics.co.uk/dna-analysis/

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&ved=0ahUKEwj20Z-Ek6zKAhXHzxQKHVuUCmEQFghZMAw&url=http%3A%2F%2Fscience.howstuffworks.com%2Flife%2Fgenetic%2Fdna-evidence2.htm&usg=AFQjCNHs9e67TIb9vcYA1n9BDYCCmBijzA&sig2=bU3R3W27UOqqn7U80B8F4g