Mass Murders in Vaster Numbers Than I Expected

There was a mass murder in Midland Co., Michigan in 1982.  I was looking looking for details.  (After he died of natural causes--Michigan has never had a death penalty--his DNA was matched to a rape-murder in the same county some years before.)  While trying to find details, I found another horrendous mass murder in Michigan, the Robison family, beaten to death, shot, or both in a cabin in Harts End, Mich.  The murder was discovered only a month later, when a neighbor went over to find out what the smell was that was disrupting her social events.