Russian ambassadors are dying at a startling rate: Russian and Sudanese authorities say Mirgayas Shirinsky was found dead at his Khartoum residence on Wednesday, making him the fourth Russian envoy to die overseas since December. Authorities say the 63-year-old was found in the residence's swimming pool after suffering an apparent heart attack, the Sudan Tribune reports. Shirinsky had been the ambassador to Sudan since 2013, the New York Times reports. Vitaly Churkin, Russia's UN envoy, died suddenly in February. Alexander Kadakin, Russia's longtime ambassador to India, died after an illness in January. And Andrei Karlov, Russia's ambassador to Turkey, was assassinated in December last year. (More Russia stories.)