Liquid blood samples are collected from blood pools or on cloths using special gauze pads. Liquid blood samples must be frozen and transported to the laboratory where it is dried because moist blood is easily attacked by microorganisms. For dried blood, the entire object could be taken, however, if this cannot be possible the stained portion is cut out. In cases where the surface cannot be cut, the sample is extracted using a fingerprint tape or the blood is scraped into an evidence container (Buckleton, Bright and Taylor, 2016). The samples must be well covered to avoid contamination In cases involving violent crimes that involve bloodshed, blood samples often belong to the victim though in cases involving a struggle, the sample may belong to the suspect. stabbings and gunshot scenes are often marked by blood stains. A DNA test is often used to identify the owner of the blood sample and put suspects in crime scenes (Buckleton, Bright and Taylor, 2016). Other blood stain analysis procedures identify how the crime was committed which is often subject to the crime scene. Investigators at times analyze patterns in the blood stains. Combined DNA Index System (CODIS) Is the FBI program that runs the criminal and Justice databases for DNA. It is the computer system that stores, manage and retrieves criminal justice DNA information. The DNA profile of the blood samples in an investigation is run against the various databases under CODIS to check for matches and place suspects in crime scenes (Buckleton, Bright and Taylor, 2016). The information stored in the database is, the DNA profile, the Agency identifier for the agency submitting a sample, the sample identification number and finally the laboratory personnel responsible for DNA profile analysis.

By Steve 4 years ago . Marked as helpful (264). Marked as unhelpful (252)