Then why did he change his story?
Because terrified people OFTEN say stupid things at moments like that. You see, they hear that some people want to turn every accident into a homicide.
Him saying he was cleaning wasn’t smart, but it doesn’t make it intentional murder,,(except on CSI Miami)
Ask any cop. People often lie when the truth would clear them. Fear makes people act stupidly, especially 21 year old who probably havent had a thing like that ever happen in his life.