New York Times, June 16, 1858.
Demented French brothers clad only in straw belts, dropping by in the wee small hours and claiming to have killed their sister: That does set the stage, doesn't it? It would make a great cold open
for an episode of Law & Order: Antebellum Michigan
, "ripped from yesterday's headlines."
The reportage here is a bit vague: They killed her on God's command because she insisted on going to church on the Sabbath? I'd speculate they were converts to Seventh Day Adventism, but that lot didn't get formally organized until 1863 and aren't generally known for practicing sororicide.