I was able to get some further details from the Cleveland Archives. His name was spelled Frank Haffner, and the cause of death was given as: "injury to spine by accident." The data said he was buried at the Monroe Street Cemetery, but I haven't seen him there yet, on any published list. He will not be buried with his wife Anna, since she survived him and went on to marry Alois Schutt in Sept 1877. If anyone comes across a newspaper account of this 'accident' on/about Oct 3, 1876, that would be great! At the time of his death, he was listed as 35 years old (he was actually a little older), and was living on Bush St.