because it is so hard to extract the blood from them. From the blood it can be figured out if the bloodstain is from a male or female. It can also tell us how many people it involved for a DNA profile of two people is far more complex then a DNA profile for one person. Specimens that are drawn from the victims or suspects are called known exemplars. They usually consist of liquid blood. The best storage for blood is frozen. Buccal or the inside of your cheek can also be supplied as exemplars. For people who cannot have blood drawn for any particular reason it is used instead of blood. Semen- Semen stains are the most common evidence to be submitted for DNA analysis. Sperm cells and non-sperm cells can, as well as blood, be separated. Tissues Isolation of DNA from tissues is a simple straightforward process. Usually, soft tissues received in the laboratory are from partially decomposed bodies. DNA last shorter in liver and kidney, longer in muscle and brain and even longer in dense bone and teeth. Sometimes DNA can be drawn from a bullet or weapon used to injure the brain or any other tissue. If a body is not recovered and only bits of tissue are then they can be used and compared with surviving family members.Chemically Treated Tissues- There are two common chemical treatments, formaldehyde for medical purposes and embalming. DNA can be drawn from both tissues. Even bodies that have been buried for several years can give results. Hair Roots- The sufficient amount of hair needed for analysis is one to five hair roots. Shed hairs contain only traces of DNA and are generally not suitable for testing in forensic use. A highly specialized method known as mitochondrial sequencing is starting to be used more and more. Saliva- DNA can be taken from saliva deposited on almost everything. Envelope flaps or stamps, as was done in the New York World Trade Center bombings. It can also be drawn from cigarette butts, cups, bo...
