Chester de Hart’s surname was spelled a couple of different ways; I’ll keep it simple by using his daughter’s version.
Chester de Hart (1883-1912) was an civil draughtsman by trade and born in New York. He was the second son of Henry Garrett Voorhees de Hart (1849-1917), a physician, and Margaret Adellaide Winship (1850-1909). He married Minna “Minnie” Sievert in 1906. Chester’s and Minnie’s only child was Elaine de Hart (1909-1993) who married Harry Helgans (1894-1965) in 1934. There were no grandchildren.
I discovered only one instance of Chester appearing in a play, Pygmalian and Galatea by Jean-Léon Gérôme, at White Plains, NY on 22 September 1903:
Indeed, a tragedy.
How interesting that even early in the 1900s his friends connected his head trauma to his ongoing emotional and physical suffering. Before shell shock, before MRIs.