Simplify the following text for a Grade 6 native English-speaking person.
Original: In the second chapter , Snape claims to have been working for Voldemort ever since the latter 's return , and only pretending to help Dumbledore . By killing Dumbledore toward the end of the novel , Snape seems to place himself firmly in Voldemort 's camp .
Simplified: Voldemort believed Snape killed him because Voldemort had planned Snape to do that .