A new book names Donovan as involved in the conspiracy to kill Patton. Haven’t read the book, don’t know how credible it is, but the death is definitely suspicious.
Just a few years ago Oliver North did a War Stories which disputed various conspiracy theories. So I don't know.
If I remember right, North concluded something along the lines of, the death Patton received was just the sort an old soldier like him would have wanted -- short of being killed in battle.
Btw, that name Donovan shows up in a number of interesting places, including as a close advisor to FDR in the months just before Pearl Harbor.