(NewsNation) — Russian oligarch Roman Abramovich and Ukrainian officials he had been conferring with as part of peace talks between Russia and Ukraine reportedly developed symptoms of poisoning following meetings earlier this month.

“They like poison; it’s like a very personal kind of death agent,” Jonathan Sanders, former CBS News Moscow correspondent and author of “The Russians Emerge,” said Wednesday night during an appearance on NewsNation’s “Banfield.”

Why would poison would be a method of choice for Putin?

“I think it’s because it’s in a fine tradition of spy-craft. When Vladimir Putin was still in high school, still studying German, watching the spy stories on TV. There occurred in 1970, a remarkable case in which a Bulgarian diplomat (was) crossing a bridge in London. Someone came up behind him with an umbrella, poked him in his leg, put ricin in his leg, and he died shortly after,” Sanders said.

“This has been something that the Kremlin has been up to for a long time, and they have a whole range of chemical agents.”

Sanders has also personally faced a death threat, by a Chechen warlord, but in that case, “he said he was simply going to cut my head off,” Sanders said.