According to Mark Twain, “Truth is stranger than fiction, but it is because fiction is obliged to stick to possibilities; Truth isn't.”
Two non-fiction true crime books passed through my hands recently that gave me reason to reflect upon this.

One is Stealing Lincoln’s Body by Thomas J. Craughwell, which is about an incident in 1876 involving several Chicago counterfeiters who attempted to steal Lincoln’s remains from his Springfield tomb. As a result, our 16th president now rests below several feet of cement.
There is an interesting twist on this story. Lincoln himself actually wrote a mystery story entitled “The Trailor [sic] Murder Mystery” which was based on a case he was involved in as a young lawyer.
It turns out that Lincoln was an avid admirer of Edgar Allan Poe!
You can find this story in The Black Cabinet, a collection of mystery short stories based on true crimes.

The second is The Daughters of Juarez: a True Story of Serial Murder South of the Border by Teresa Rodriguez. It is an account of the mutilations and murders of hundreds of young women between 17 and 22 years of age since 1993 in Juarez, Mexico that remain unsolved.
One of the comments on the back cover by mystery writer Edna Buchanan caught my eye: “This story is more horrifying than a Stephen King novel, has more twists and turns than an Agatha Christie plot, and a higher body count than any James Bond flick.”
There is actually a mystery novel involving “las feminicidios de Juárez” called Desert Blood by Alicia Gaspar de Alba. After El Paso native Ivon Villa (called “unforgettable” in a Booklist review) returns to her hometown to adopt a baby, the mother of the child turns up as one of the victims. When her younger sister is subsequently kidnapped in Juarez, Ivon decides to do whatever it takes to get her back despite the warnings of her family, friends, and nervous officials.
It is no wonder that true crime inspires so much powerful fiction. If you made up some of the real things that have happened, a reviewer would undoubtedly call your plot “implausible.”