In 2004, Viktor Yuschenko was Ukraine’s most promising candidate to oust Leonid Kuchma, an unpopular president who served for a decade and enjoyed close ties with Russia. Yuschenko won the election later that year, but at a steep cost: he’d been poisoned with a near-fatal amount of dioxin, which left him disfigured and seriously ill. In the aftermath, Ukraine’s highest prosecutor investigated whether the apparent attempt on Yuschenko’s life was the work of the Kremlin, but in the decade since, the poisoning has never been solved.

Alexander Litvinenko, a former KBG officer turned Russian dissident, died in 2006 after drinking green tea laced with polonium 210 in the company of two Russian men at a hotel bar in London. A British inquiry into his murder has found that Vladimir Putin “probably approved” it.

During the final day of a public inquiry into Russian dissent Alexander Litvinenko’s death, a lawyer for Litvinenko’s widow said Vladimir Putin “personally ordered” the apparent assassination. Litvinenko, a former FSB and KGB spy, died in November 2006, three weeks after drinking tea laced with the radioactive element polonium-210 during a meeting at a London hotel.