Final answer:
Britten thinks bigger is involved in Mary's disappearance based on his analysis of the evidence and the emphasis on American dollars being a distraction. He rules out Mr. Moriarty and intends to find more clues through newspaper examination.
Step-by-step explanation:
Britten believes that bigger must be involved in Mary's disappearance due to his analysis of the evidence. He concludes that the emphasis on American dollars is a distraction and suggests that a native of Britain is the likely perpetrator. Britten dismisses a suspect named Mr. Moriarty based on their behavior pattern, ruling them out as a cat attacker. By sending copies of London newspapers to review, Britten hopes to find any missed clues that could shed light on the case.