ThreatActor associated with a Sighting?

["Memory, Alexander C." <ALEXANDER.C.MEMORY@leidos.com>]

I am new to STIX and have a question about how to use it.  Suppose that a sighting of some indicator can give us knowledge of which threat actor is involved.  In that case, I would want to associate a STIX ThreatActor with a Sighting, but I don’t see how to do that using STIX 1.2.  I see how the Indicator can be related to a ThreatActor through a Campaign, but I need to associate a specific ThreatActor to a specific Sighting.  Is this the wrong way to use Indicators and Sightings?

Alex Memory