In the article:
Every Motive Being Eyed In Concord Double Homicide Case: Investigators
the daugher Lindsay reponds to rumors that her parents were involved with the CIA:
She makes the case that her parents weren't the kind of people that would get involved in sketchy things like that. But the article continues to discuss that there sometimes are blurry lines between USAID and CIA:
The Reids have worked a lot in African countries. Some of these countries politically unstable. I imagine that in their work they had to deal with local politicians and other leaders. I imagine that there are risks to do this kind of work, although it seems unlikely that it would get you killed within the US borders. I think that US intelligence agencies would be interested to learn from experiences of people that work on local projects in countries that are in turmoil. But this doesn't mean that the Reids worked for the CIA, or were in anyway involved with the CIA.
What also may have added to the CIA rumors is Stephen Reid's work for Tetra Tech. We know very little about the work he did there. This is a big company that is involved in many projects, ranging from aid to developing countries to defense projects. Could anyone in the company, or who interacted with Stephen Reid representing Tetra Tech hold a grudge against the Reids?
There are few plausible motives for the murder. I think a hate crime is possible, but I cannot discount the possibility that the murders are related to the work that Steve and Wendy were involved with. We don't know enough about this work to understand what could have led to a murderous grudge.