Answer:
so it is likely that Ratchett was murdered by one of the passengers on the train. Evidence to support this includes the fact that the train was stuck in a snowdrift and no one was able to get on or off the train. This suggests that the murderer had to be one of the passengers. Additionally, the murderer's plan involved leaving the train before the police arrived, so whoever killed Ratchett had to have been on the train. This evidence leads to the conclusion that Ratchett was killed by one of the passengers on the train.