Hint on 'blackmail' evidence
Mr. White’s Ghost has something interesting to say about this.
Hint on 'invitation' evidence
Mr. Black doesn’t appear to see this the same way as everyone else.
Hint on 'report' evidence
Mr. Yellow might be interested in this as the CFO.
Strong hint 1
Mrs. Red is Mr. White’s wife.
Strong hint 2
Mr. Black’s statement about seeing the murderer seems strong, but maybe he didn’t see everything correctly.
Strong hint 3
Mr. Yellow didn’t want the report getting out, and said ‘she’ would bury it. Who is ‘she’?