On this page find: Forensic science is the application of sciences such as physics, chemistry, biology, computer science and engineering to matters of law. Forensic science can help investigators understand how blood spatter patterns occur (physics), learn the composition and source of evidence such as drugs and trace materials (chemistry) or determine the identity of an unknown suspect (biology). Forensic science plays a vital role in the criminal justice system by providing scientifically based information through the analysis of physical evidence. During an investigation, evidence is collected at a crime scene or from a person, analyzed in a crime laboratory and then the results presented in court. Each crime scene is unique, and each case presents its own challenges. NIJ supports research and develop in the following forensic science disciplines: Learn about NIJs forensic science research priorities. NIJs forensic science research and development program focuses on basic and applied scientific research with the intent to: Expand the text below to see examples of scientific issues addressed by forensic science research and development. Pattern and Impression Evidence: Quantifying qualitative comparisons [Read more...] The issue: Forensic analysis of impression and pattern evidence (e.g., latent fingerprints, firearms, shoe prints, blood patterns) has traditionally … Continue reading →

In molecular biology, the term double helix[1] refers to the structure formed by double-stranded molecules of nucleic acids such as DNA. The double helical structure of a nucleic acid complex arises as a consequence of its secondary structure, and is a fundamental component in determining its tertiary structure. The term entered popular culture with the publication in 1968 of The Double Helix: A Personal Account of the Discovery of the Structure of DNA, by James Watson. The DNA double helix polymer of nucleic acid, held together by nucleotides which base pair together.[2] In B-DNA, the most common double helical structure found in nature, the double helix is right-handed with about 1010.5 base pairs per turn.[3] This translates into about 20-21 nucleotides per turn. The double helix structure of DNA contains a major groove and minor groove. In B-DNA the major groove is wider than the minor groove.[2] Given the difference in widths of the major groove and minor groove, many proteins which bind to B-DNA do so through the wider major groove.[4] The double-helix model of DNA structure was first published in the journal Nature by James Watson and Francis Crick in 1953,[5] (X,Y,Z coordinates in 1954[6]) based upon the … Continue reading →

Consuming a pack of cigarettes every day for a year can cause multiple changes in cells within various parts of the body, according to the study, published in the journal Science on Thursday. The cells in parts of the body that are directly exposed to smoke are particularly damaged, with 150 mutations found to occur in lung cells within one year, 97 in the larynx and 39 in the oral cavity. "Tobacco smoking damages DNA in organs directly exposed to smoke as well as speeds up a mutational cellular clock in organs that are both directly and indirectly exposed to smoke." said Ludmil Alexandrov of the Los Alamos National Laboratory in Los Alamos, New Mexico, who led the study. In other words, it accelerates the occurrence of genetic mutations, increasing the risk of cancer. "Before now, we had a large body of epidemiological evidence linking smoking with cancer, but now we can actually observe and quantify the molecular changes in the DNA due to cigarette smoking," Alexandrov said. Tobacco smoke is a mixture of chemicals, of which 60 are known to be carcinogens thought to cause cancer by aiding the occurrence of mutations within genes. With an increased number of … Continue reading →