Njiru's first national track final was in 2012, when he finished 6th in the 3000 metres steeplechase at the Kenyan Athletics Championships with a time of 8:37.2.

[2] Njiru ran four half marathons in 2017, improving his personal best to 1:02:19 at the Semi-Marathon International de Berkane in Morocco.

[2] In December, Njiru improved his 3000 m steeplechase personal best by one tenth of a second, running 8:31.3 to win a meeting in Machakos, Kenya.

According to Nyandarua County police, Njiru lost control of his own car towards the famous equator line on the road, which caused it to collide with the Land Cruiser.

Three tourists of Russian origin in the Cruiser were injured from the accident and taken to the hospital in critical condition, while Njiru was proclaimed dead on the spot.