If the CIA, the Ukrainians or the French took Prigozhin out, I would expect the Russian FSB and military intelligence to take a retaliatory action against a high official of those governments. I have no doubt the FSB, like the KGB before them, has extensive spy networks in this country. With the rise of Cold War II, the weak border controls with both Mexico and Canada, and the focus on domestic intelligence on "right wing extremists", it is likely the Russians have the capacity to strike at a top U.S. military or foreign policy official.
That being said, it is more likely that the apparent death of Prigozhin is an internal Russian matter, possibly within the Wagner Group or as revenge by the Russian military.
—> If the CIA, the Ukrainians or the French took Prigozhin out,
Not out. Just provided targeting intelligence.
According to reports