http://www.d20pfsrd.com/classes/hybrid-classes/investigator/archetypes/paiz o-investigator-archetypes/forensic-physician-investigator-archetype/
I'm sure it's way too late, but there is a investigator archetype that seems tailor made for what you were asking for. Maybe multiclass with something that gives you access with speak to dead. But other than that I think you're good to go.
