Complex sentence: Damien Andre Gates fired the shot that entered through the trunk of the vehicle that Santana was in, the bullet penetrated the right-front passenger headrest and entered directly into Santana's head killing him instantly.
Split into simpler sentences: Damien Andre Gates fired the shot that entered through the trunk of the vehicle that Santana was in. The bullet penetrated the right-front passenger headrest and entered directly into Santana's head, killing him instantly.