Ndiema was accused of attacking Cheptegei at her home in Trans Nzoia over an unresolved land dispute.
He allegedly ambushed the marathoner as she returned home, before dousing her with petrol and setting her alight.
Efforts by the athlete to save her life were unsuccessful as her attacker continued to douse her with more petrol.
Ugandan marathoner Rebecca Cheptegei's ex-boyfriend and alleged killer, Dickson Ndiema Marangach, who died on Monday, was an athletics “coach” assistant.
According to the 800m and 1,500m Kenyan athlete, Isaac Ruto, Dickson moved to Endebes from his hometown in Masek, Mount Elgon to escape the clashes in the region. In Endebes, he used to help athletes during their training and competitions.
