48 Hours: Hard Evidence

Police find the wife of a California fertility doctor dead at the bottom of a staircase in their San Clemente home. Did her dogs play some role in her death or was the scene staged to cover up a murder? Correspondent Tracy Smith reports.

The investigation into the death of Sarah Harris raises questions about the relationship between a doctor and his much younger girlfriend.

Officers arrive at a nurse's apartment to find her lying dead in the bathroom; a security camera captures her coming home for the last time; can authorities piece together the evidence to determine if this was suicide or murder?