George Olivo, a retired FBI special agent and senior polygraph examiner, on how polygraph tests work and their reliability.

Posthumous DNA testing proved what Roger Keith Coleman repeatedly denied—that the Virginia man raped and murdered his sister-in-law in 1981.

After Candra Torres's husband was murdered by a man they had just met, she corroborated the stranger's story that it was an accident. But days later, she changed her story. Read Candra's story, which inspired the Lifetime movie, 'A Murder to Remember.'

How sound is the reasoning that a refusal to take a polygraph test is a sign of guilt? We speak to former polygrapher and current anti-polygraph activist, Douglas Williams, about what he sees as the test's fundamental problems.