At the crack of dawn in residential Newcastle, a man is violently assaulted and stabbed in his home by two unknown assailants. The suspects flee the scene and it is the job of rookie CSI Nicola Stark to examine the crime scene and surrounding area to find the clues that could lead her to identify the attackers. Impressions are taken of footwear marks left in blood at the scene, and a carelessly disposed kitchen knife could also provide fingerprints of DNA, but it is an eerie homemade balaclava which catches the attention of Nicola’s boss, head of forensics Kirsty Potter, who believes it could be the key to finding the identity of the attackers - “balaclavas are great in any offence. Something that’s removed quick-time from an offender could have hairs, saliva and saliva will persist on fabric”. The mask is fast-tracked to the lab where saliva and blood tests provide a DNA match to one suspect. But with a second suspect still at large, does the other evidence found by Nicola at the scene hold the clues to his identity?

In Sunderland, a woman reports being raped by two unknown men in a block of flats. Intimate samples are immediately taken as these provide the best chance of identifying the unknown suspects and bringing them to justice. But with two different, and as yet unknown people’s DNA present in the samples, identifying individual DNA profiles for comparison with the national DNA database is no simple matter. Show less