When a murder has occurred, forensic science can be essential for proving the identity of both victim and killer. Some killers have wrongly assumed that the absence of a complete body, or the removal of distinguishing features such as fingerprints, would prevent the identification of a victim. The combination of different types of forensic science, in particular dentistry, pathology and entomology, can be used to establish the identity both a victim and their killer. Far from needing a complete body, analysis of only small remnants of a person, such as teeth or fragments of bone, can be used to confirm who a victim was. It is not so easy to dispose of a body, and that evidence is left behind even when a corpse is subject to fire or acid. DNA profiling (sometimes called DNA fingerprinting) can be used to establish the identity of a suspect. DNA is made from molecules called nucleotides that are joined together to produce a long chain. In fact, DNA is comprised of two of the long nucleotide chains that wrap around each other to form a helix. The discovery of the DNA helix in 1953 by Francis Crick and James Watson was a critical breakthrough in understanding the genetic inheritance. For their discovery, Crick and Watson (and their colleague Maurice Wilkins) were awarded the 1962 Nobel Prize in Physiology or Medicine. The nucleotides within the DNA chain have a chemical component called a nucleobase. There are four different nucleobases that make up DNA, They are adenine, thymine, guanosine