DNA is the material in cells that stores a person's inherited traits. DNA can be collected from small amounts of blood, mouth (cheek) scrapings, hair roots, or other biological samples. There are two kinds of DNA in the body, nuclear DNA and mitochondrial DNA. Both kinds of DNA can be used for identification. In many, but not all, cases, DNA can be isolated from human remains. DNA testing can be one of the best methods for identifying a victim. In order for DNA testing to be useful, there must be a way to compare the DNA obtained from the unknown victim with that of a missing person suspected of being the victim. DNA from the missing person's previously collected medical specimens or personal items can be used for comparison with the DNA of the unknown victim. Medical specimens with DNA include a bone marrow sample or a biopsy sample. Personal items that can contain DNA are a toothbrush or a hairbrush. If such items do not exist, DNA testing can be done on samples from blood relatives, preferably the missing person's biological mother, father, children, brothers, or sisters.