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Its accuracy has made DNA evidence virtually unassailable. A landmark report published by the National Research Council in 2009 dismissed most forensics as unproven folk-wisdom but singled out DNA as the one forensic science worthy of the name. Yet in recent years Hampikian and other geneticists have begun to question the technology. Thanks to a series of advances-including the polymerase chain reaction, which can multiply tiny amounts of DNA-it's now possible to detect DNA at levels hundreds or even thousands of times lower than when DNA fingerprinting was developed in the 1980s. Investigators can even collect "touch DNA" from fingerprints on, say, a glass or a doorknob. A mere 25 or 30 cells will sometimes suffice. This heightened sensitivity can easily create false positives

Students use DNA profiling to determine who robbed a bank. After they learn how the FBI's Combined DNA Index System (CODIS) is used to match crime scene DNA with tissue sample DNA, students use CODIS principles and sample DNA fragments to determine which of three suspects matches evidence obtain at a crime location. They communicate their results as if they were biomedical engineers reporting to a police crime scene investigation.

Forensic Science explained from the US Department of Justice

Graham Williams at the University of Huddersfield, UK, has a different way - to look for modifications to the twins' DNA that have come about as a result of their lifestyles. Such epigenetic changes occur when a chemical group known as a methyl group attaches to a gene and modifies the way it is expressed. This happens as a body is influenced by a person's environment, lifestyle and disease.

How can a mixture of molecules, too small to be seen with even a high-powered microscope, be separated from one another? Such was the dilemma facing scientists until the development of a process that is now standard in laboratories worldwide-gel electrophoresis. Laboratories rely heavily on this proven and reliable technique for separating a wide variety of samples, from DNA used in forensics and for mapping genes, to proteins useful in determining evolutionary relationships.

Variety of lesson resources

Links to wide array of virtual labs

Trialer for book written about the wrongful conviction of Ronald Cotton

We create interactive lessons for high school and college educators to engage their students in discussions of ethics and personal genetics. The lessons are relevant to multiple subjects, including biology, health, social studies, law, physical education and psychology. All of our lesson plans contain background reading for teachers and students, a selection of classroom activities, discussion points, in some cases a slide presentation or video clip, and an evaluation. Each lesson can stand alone, or all the lessons can be taught as a unit.