The Primary Chronicle says Sviatopolk had his brothers Borys and Hlib killed in 1015, and Yaroslav buried them as saints after taking Kyiv

Volodymyr the Great had 11 sons by five wives and set them over the lands of Rus' to govern and collect tribute. Late in his reign his sons Sviatopolk of Turiv and Yaroslav of Novgorod defied him. He died at Vyshhorod on 15 July 1015 while preparing a campaign against Yaroslav. Sviatopolk took Kyiv that month. Modern scholars think he was probably the son of Volodymyr's brother Yaropolk. The Primary Chronicle says Sviatopolk ordered the deaths of his brothers Borys, Hlib and Sviatoslav, and calls him "Okaiannyi," the Accursed. Church tradition says killers attacked Borys in his tent by the Alta River and that Hlib, near Smolensk, was killed by his own cook on the order of a man named Goriaser. Yaroslav called his war on Sviatopolk revenge for the brothers. He beat him at Liubech in 1016, lost Kyiv to him and his father-in-law Bolesław I of Poland in 1018, and defeated him on the Alta in 1019. Sviatopolk died fleeing west. In 1019 Yaroslav had the bodies exhumed and buried in Saint Basil's Church at Vyshhorod. Borys and Hlib were canonized about 1068, the first saints of Rus'. The historian N. N. Ilyin argued that Yaroslav, not Sviatopolk, was the killer. In 1240, when Batu's army took Kyiv, the relics were hidden, and where they lie now is not known.