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 had a radically different account. 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.