How can a woman vanish without a trace?

On a Sunday morning more than three weeks ago, Ballarat woman Samantha Murphy set out for a run in dense bushland not far from her home. She was expected back mid-morning for a family gathering, but she never arrived.  Police have now wound back their search for the missing mother, while locals have rallied to try and find answers.  Today, what happened to Samantha Murphy? Featured:  Norman Hermant, 7.30 reporter