Felix Grundy Stidger died on 12 May 1908 in Chicago. His death was reported in newspapers around the country. Stidger's autobiography recalls in fascinating detail how he quickly made the acquaintance of the leaders in the Sons of Liberty and exposed their plots against the US Government as part of the Secret Service in 1864. It looks like he spent years trying to get a pension from the government, and still did not have it in 1904. There is probably a large file on him at the US National Archives.
Ancestry. Civil War pension card for Felix Stidger.
I could spend quite a long time going through Stidger's book and sharing news clippings of testimony in the case that brought down the Sons of Liberty, but I am going to return to the Holsclaw family soon, leaving behind Stidger's fascinating story for another researcher to pick up.