How is blood from a crime scene tested and how is contamination prevented?
In addition to the above post, It is VERY IMPORTANT that ANYONE on the crime scene is required to wear protective footwear such as paper slippers and gloves which prevent them from carrying anything to or from the crime scene on the soles of their shoes or in the case of the hands, leaving finger prints at the scene. It is also important to remember that at the scene of a crime the first police officer – or officers – has the responsibility of cordoning off the area to ensure that no one enters or leaves. This is designed to ensure that no cross contamination occurs. On occasion the officers who are first on scene will be required to provide their fingerprints to rule out any fingerprint evidence that may have been contaminated by their touch.
