A question that comes up in mystery stories is having characters who are above suspicion. In golden age mysteries it was extremely popular to make precisely these people the murderer. Sometimes it was even a game to try to make the murderer as far above suspicion as possible. I am coming to think that this is a mistake, though, or at least that it can be.
Casting my eye over my favorite mysteries, the most interesting characters are usually the ones who are above suspicion. These are the people who are affected by the mystery but are not part of it; they’re the most interesting because we can take them seriously. People who are under suspicion are part of the mystery and thus everything that they do, say, and (appear to) think is all suspect.
To be fair, this is at least partially remedied upon re-reading. Knowing who is and who is not false lets us take the true characters seriously. However, this is only a partial remedy because the other characters in the story cannot trust the suspected characters and thus cannot form meaningful relationships with them.
Now, it is necessary in a mystery story to have suspects, and the plural is important. I’m not trying to suggest that one should do without them. Worse, if one had no suspects then everyone would be a suspect. The key, I think, is the distinction between suspect and non-suspect. Some people must be seen to be under suspicion, and others must be clearly elevated above it in an authentic way. But how to do that, especially when the game in golden-age mysteries was to elevate the murderer above suspicion as much as possible?
Obviously recurring characters help a great deal in this. No one suspects Amos Tupper or Seth in Murder, She Wrote since we know that they’ll be back in future episodes and that Cabot Cove wouldn’t be the same without them. It is also typical that people who were called into the mystery after the crime was committed are above suspicion, hence the police and the detective usually are. This is not always so, though; occasionally people who show up later were there before, secretly. Newcomers are actually above suspicion when they have what makes anyone above suspicion: an alibi.
Of course, in mysteries, alibis are made to be broken. The more cast-iron the alibi, the greater the glory in breaking it.
Some alibis simply stand, though. Being seen continuously in front of unimpeachable witnesses from before the last time someone was seen alive until after they were found dead is, in fact, unbreakable. As long as it wasn’t murder by poison, booby-trap, or anything else that doesn’t require the murderer to be present.
And it doesn’t rule out accomplices.
So, other than a character being a recurring character, is there a way to make someone above suspicion so that the reader can take them seriously and the characters can form meaningful relationships with them?
I think that there is, at least sufficient for our purposes: the author can treat the character as above suspicion. That is, not only is the character established to have a good alibi, but the author proceeds on that basis. The character is given development and other characters form meaningful relationships with them. The possibility of their alibi being breakable, for the wrong time, or irrelevant because of an accomplice is simply never brought up. In effect, the author gives the detective confidence in the character and this allows the desirable consequences.
The example of this which comes to mind most readily is the character of Dean Letitia Martin in Gaudy Night. Harriet tells the dean that she simply refuses to consider her a suspect because the dean is too level-headed. Dean Martin objects that this isn’t really valid, but doesn’t otherwise object since she knows herself to be innocent. And the story proceeds with Dean Martin being an interesting character.
(What brings this to mind is that the character of Rhodri Ap Huw, in my favorite Cadfael story, Saint Peter’s Fair, was partially wasted because Ellis Peters held him out as a suspect.)