Complex sentence: Continuing their search for answers about Charles, Alison, Jason, Hanna, and Spencer later discovered Charles'grave behind Carol's house; they now believe that'A' was using Charles' identity.
Split into simpler sentences: Continuing their search for answers about Charles, Alison, Jason, Hanna, and Spencer later discovered Charles'grave behind Carol's house. This discovery led them to believe that'A' was using Charles' identity.