Deckare is the Swedish word for crime novels or other fiction; as you may have noticed, Swedish authors are fairly fond of these and the country has a strong tradition in detective fiction.
Although it usually refers to books, a TV series or film can also be a deckare. A similar English word would be 'whodunnit'.
The term comes from a shortening of detektiv (you probably don't need to be a 'detective' to work out that that's the English translation), since the protagonist in these stories is often a private detective. But books featuring a police officer, journalist, or a mystery-solver of another profession can also fall under this heading.
One of the key defining features of the deckare is that the reader must have the same chance as the detective to solve the murder, meaning that all clues should be clear to readers as well as characters.
Deckare (the plural form is the same as the singular) have boomed in popularity over the past few decades, making up an increasingly large proportion of the bestseller lists in Sweden.
Du har läst för många deckare
You've been reading too many detective novels
Henning Mankell har skrivit flera deckare
Henning Mankell has written several detective novels