Of course not, the emphasis should be on mystery.
I think in one episode of Midsomer they completely lost count about the bodies and one of them lay there unexplained.
This G. K. Chesterton quote is a good description of a mystery formula:

"I like detective stories; I read them, I write them; but I do not believe them. The bones and structure of a good detective story are so old and well known that it may seem banal to state them even in outline. A policeman, stupid but sweet-tempered, and always weakly erring on the side of mercy, walks along the street; and in the course of his ordinary business finds a man in Bulgarian uniform killed with an Australian boomerang in a Brompton milk-shop. Having set free all the most suspicious persons in the story, he then appeals to the bull-dog professional detective, who appeals to the hawk-like amateur detective. The latter finds near the corpse a boot-lace, a button-boot, a French newspaper, and a return ticket from the Hebrides; and so, relentlessly, link by link, brings the crime home to the Archbishop of Canterbury."

Some good essays here