Mystery at Cook Manor

Once elegant and lively, the Cook Manor has slowly fallen into disrepair. As an iconic building, you cannot pass up an invitation from the owner himself, Mr. Artemis R. Cook. However, the messenger also delivers two shocking pieces of information. First, one of you is in fact a distant relative of the Cooks. Second, and most interestingly, Mr. Cook DIED shortly after sending this message. Can you unravel the events and solve this whodunit??