According to an autopsy conducted by Chief Government Pathologist Johansen Oduor on Wednesday, Kiptum died of severe head, spine and rib injuries.
He said the late Kiptum's spinal cord was seriously injured during the road crash.
The government pathologist said samples collected from Kiptum's body would be taken for toxicology analysis.
Kiptum's father, Samson Cheruiyot, and several relatives and friends witnessed the postmortem examination conducted ahead of athlete's burial tomorrow.
The only survivor in the tragic crash that Kiptum and his Rwandan coach claimed she alerted the athlete immediately after the ill-fated car suddenly started veering off the road.
"After shouting, the vehicle accelerated far off the road, landing in the ditch before hitting a wall. That was the last thing she remembers," the source said.
Initially, however, the car was said to have hit a tree after veering off the road.
Photos by Lynn Kolongei and Christopher Chesang.