George DeMohrenschildt was "very likely" or just possibly a KGB asset?
According to Richard Russell in
The Man Who Knew Too Much, Petty thought DeMohrenschildt fit the bill because, like a particular "Illegal" in the VENONA decrypts:
1. He was born "maybe in Poland" (300 miles from the Polish border in Byelorussia).
2. He emigrated to the U.S. before WW II (1938).
3. He lived in Mexico during WW II. (With his girlfriend, Lilia Pardo Larin.)
4. He was a wheeler-dealer. (sugar speculator, oil speculator, real estate salesman, marketer of his own artwork, etc.)
Take it up with Dick Russell if you want to.