http://www.kasparov.ru/material.php?id=5BF9C789DF3A4
“Natural causes” can’t be ruled out. But those include stress, and there’s no doubt Gen. Korobov of the G(R)U was under a lot of that.
https://www.thedailybeast.com/inside-the-mystery-of-the-dead-russian-spy-chief
https://www.gazeta.ru/army/2018/11/24/12070387.shtml
http://www.kasparov.ru/material.php?id=5BF9252437A4D
https://www.gazeta.ru/social/2018/11/24/12070363.shtml
https://www.inopressa.ru/article/23Nov2018/wp/pence.html
https://www.inopressa.ru/article/23Nov2018/forbes/cyprus.html
https://www.radiosvoboda.org/a/donbass--realii/29617362.html