Scientific Evidence

The first American crime laboratories were established about 1930. The principal techniques used in these laboratories were fingerprinting, handwriting comparisons, toolmark and firearms ("ballistics") identifications, drug analysis, blood tests, and trace analysis (hair, fiber, and glass). However, by the late 1960s the nature of scientific evidence had changed dramatically; new techniques had been developed, and courts faced decisions about the admissibility of testimony based upon a much wider array of scientific techniques: sound spectrography ("voiceprint"), neutron activation, atomic absorption, electrophoretic blood testing, scanning electron microscopy, mass spectrometry, gas chromatography, and bite mark comparisons. Even fingerprint identification had moved into the high-tech age with laser technology for visualizing latent prints and powerful computers for searching databases including millions of sets of prints.