"All white juries almost always found abusive slave owners "not guilty" of committing crimes against slaves, as slaves were seen as secondary citizens."

No, slaves were not seen as secondary citizens. Slaves were not seen as citizens at all, but rather as property.

What are two or three examples of cases in which all-white juries found slave owners not guilty of crimes against slaves? Under which specific laws were they prosecuted?

I am highly skeptical of this claim because there were very few protections for slaves, being that they were seen as property. A slave had virtually no power to protest against beating, rape, and other abuses.