DNA analysis identifies an individual's unique genetic pattern, called a genotype. This information can be compared with other genotypes for purposes of identification. mtDNA is the DNA from the maternal side which can trace the evolution of the H. sapien from which both modern man and neanderthals are derived.
In the below articles geneticists have used mtDNA to confirm that modern man and neanderthal man are not related although they both roamed some of the same territories during the same period. As I read Janet Browne's Darwin's Origin of Species I was struck by how the genetic sciences continue to reveal evidence of adaptation (or the lack thereof), confirm natural selection, fill in missing links and present physical evidence.