Still haven't found the graves, but found an obit for Lorenz.
Andrew Heller, an old man over 70 years of age, residing four miles north of Revillo, was rolled and trampled by an infuriated bull on Monday afternoon, and died from the effects of the injuries the same night. The animal was dehorned and the old man was endeavoring to drive it into the stable with a pitchfork when it turned upon him.
--Grant County Review, March 10, 1892, page 5
Andrew was the son and the over 70 year old was Lorenz.