What or who causes Eva's death in the novel, One by One?

La Sorcière is the black, or highly challenging, ski run that begins at the top of the mountain. Liz tricks Eva into coming to her at the beginning of this run by pretending there is something wrong with her ski boot. Once Eva is bent over looking at the boot, Liz pushes her, causing her to fall to her death down the steep cliff that borders one side of this ski run.