Frankenstein: Creature

Mary Shelley dedicates several of the first few chapters of Frankenstein to giving details about the creature.  I was surprised at the fact that, while only being two years old, the creature was unbelievably eloquent in the English language.  He has clearly learned a great deal in his first years of living, and he is learning how to read and sympathize with the emotions of humans by observing a family from a back shed.  The creature, based on his inner thoughts and actions, is not an evil, murderous being, but a gentle and caring one.  "I saw no cause for their unhappiness; but I was deeply affected by it" (Shelley, 77).  The creature, saddened by the sufferings he witnessed of this family, decided to help them as much as he could.  He doesn't want to be seen, however, for obvious reasons.  I am finding it harder and harder to believe that this creature was William's murderer.  He is not a cold-hearted monster.  He would have had no reason in killing the boy, and it would only have made him feel deep remorse and guilt for his actions.  A creature who goes out of his way to secretly support an impoverished family would not savagely strangle a child.  But, if the creature did not kill William, who did?