It took me what seemed like forever to find a death date for my 3x great-grandfather, Richard Toner. After immigrating to Brooklyn circa 1850, he shows up there on censuses with his family, and in city directories on a regular basis. The family never moved outside of Red Hook, Brooklyn, and really lived in only a handful of addresses around 1 or 2 blocks on Van Brunt Street, by Tremont (now Visitation) and Verona Streets.
And then they just disappear. My last sighting of Richard was an 1880 Brooklyn City Directory, but I couldn't find him in the 1880 census, even though I had his address. I couldn't find anyone in the family in the 1880 census. In 1892, one of their daughters shows up, married and living with her husband and children, but Richard, his wife Mary, and the rest of their children are nowhere to be found. I was able to find deaths for both Mary and their son William in 1899, and (some of) their married daughters show up in the 1900 Census, but family is almost entirely absent from any records I've encountered between 1880 and 1900 - and Richard never shows up again after 1880. I figured he died in there somewhere, but 2 decades is a long time, and I couldn't find him in the NYC death index at the Italian Genealogical Group's site.
Luckily, I had some time ago met a cousin through Ancestry whose tree showed her as being descended from Richard's daughter - Elizabeth Jones Loughlin Renehan. I knew well that Elizabeth's name wasn't Jones, but rather Toner, but without having seen it thus misinterpreted, I might not ever have spent as long trying to think of what letters look like the letters in the name Toner. Jones was my first guess, since I knew that at least one person had misinterpreted a written Toner as Jones, and I did order the death certificate for one Richard Jones who had died in 1886, but he wasn't my guy. After thinking a little harder, I realized that Fones or Foner would look even more like Toner, and I found one likely entry in the death index - a [horribly mistranscribed] Ricehhrd J. Foner. When the certificate arrived, I knew without a doubt that I'd found my guy.
The certificate very clearly doesn't say Ricehhrd Foner, but Richard Joseph Toner. He died on 11 May 1880, so it would make sense that he wasn't on the 1880 Census, which was enumerated on 1 June 1880 - although that doesn't explain where the rest of the family was. His place of death was 91 Tremont St., which is not an address I'd seen the family at before, but it's certainly within that same radius of a block or so in which the family lived for years. His occupation and birthplace are right - he's an Irish-born painter - and his age is more or less as would be expected. He died after suffering from hepatitis for 10 days.
Richard was buried at Holy Cross Cemetery in Brooklyn on 13 May 1880. I called the cemetery once to see if they could give me a burial location or a death date, but although they were able to tell me that a Richard Toner was the owner of a plot where several of his relatives were buried, they couldn't verify whether he himself was in that same plot.
Next step: Now that I have a death date, I need to call back and find out what other information Holy Cross might be able to give me.