Thanks, CTJ! I used your suggestion of John Wilkes Booth. But only now I tried to verify this and I got http://www.factcheck.org/2022/04/posts-make-unfounded-claims-about-political-affiliation-of-john-wilkes-booth/. It says he belonged to the "know nothing" party.
Thanks, Monkeytrots, for your mention of the BLM police shootings.
http://www.nbcnews.com/storyline/dallas-police-ambush/protests-spawn-cities-across-u-s-over-police-shootings-black-n605686
I looked it up, but the article implies no membership in BLM (only sympathy) and does not mention his political affiliation.