whydunnit

/ ˈwaɪˌdʌnɪt /

noun

1. informal,  a novel, film, etc, concerned with the motives of the criminal rather than his or her identity

Example Sentences

Never in recent memory has an Australian criminal case been so high-profile: a small-town murder mystery with a weapon so outlandish it wouldn't seem out of place in an Agatha Christie novel - not so much a whodunnit as a whydunnit.

From BBC

The "whydunnit"— what would prompt someone to betray their country? — is more intriguing than the "whodunnit," but not by much because "All the Old Knives" does not provide enough backstory.

From Salon

The Guardian called it ”a fantastically compelling, brilliantly scripted whydunnit.”

From Seattle Times

Ms. Greene called the novel “not so much a whodunnit as a whydunnit,” inspired by a similar 1984 murder in Bangor, Maine.

From Washington Post

At the moment we’re just following the narrative of the murderer; it’s a whodunnit rather than a whydunnit.”

From The Guardian