At 7:00 P. M., Mrs. Wilson's maid served her tea in the library. The maid noticed that Mrs. Wilson seemed upset and a little depressed. At 8:45 P. M., the maid knocked
on the library door and got no answer. The door was locked from the inside. The
maid called Inspector Sharpe and a professor friend. When the door was forced
open, Mrs. Wilson was found dead. The maid burst into tears, crying, "I feel so bad
that we haven't been getting along lately!" Nearby was a half empty teacup, a tiny
unstoppered vial, and a typewritten note that said, "Blessed are the poor for they
shall be happy." The window was open. When the two men went out-side to inspect
the grounds, Charles, the wealthy widow's sole heir, arrived. He was told his aunt
was poisoned and said, "How terrible! Poisoned? Who did it? Why was the door
locked? Had my aunt been threatened?" He explained he had been working late at
the office and was stopping by on his way home.

a. Who are the possible suspects in this case?
b. For each suspect, identify the evidence that exists that could be used to
charge them with the crime.