On Friday, I had made some headway on my father's line. You can read about it here.
Over the weekend, I found another piece of information that pretty much tells me I'm a darn good detective. Below is a brief summary of the finds and why my theory may actually be fact. (I did send the letters I stated in Friday's post and hopefully any responses will further my claim.)
2008-11-17 Research Notes for Theresa CAHILL
I am fairly certain that Theresa "Tessie" Karas, the person my grandfather John Francis CAHILL went to live with after his mom died, is actually Tessie CAHILL, daughter of John T CAHILL and Anna L GLYNN.
I have the memorial card for Tessie, which has her death date as 17 May 1986; the funeral was at Rossi Brother Funeral Home in Youngstown, Ohio. From that, I was able to find her death record indexed on Ancestry in both the SSDI and Ohio Death Index. Both list her birth date as 8 August 1895.
On an unrelated search, I came across as Theresa/Tessie Cahill in the 1900, 1910, and 1920 censuses; father John T, mother Anna/Annie. In the 1900 census, it lists Tessie's birth as August 1895. At this point, I was pretty sure Tessie was family, and not a family friend as originally suspected.
I then searched the Illinois Marriage Index and found a listing for a John T CAHILL and Anna L GLYNN, married on 27 September 1892. This matches up with the 1900, 1910, and 1920 censuses.
Tessie's son's middle name Glynn. Because Tessie's son's middle name is unusual and happens to be Anna's last name, this (along with the above information) solidifies for me, that Tessie Karas and Tessie CAHILL are one in the same.
So what do all you experienced genealogists think? Is this a shot in the dark? Is this considered "proven?" Do I need more proof? Leave a comment to weigh in.