In "Faceless Killers," Henning Mankell highlights a crucial aspect of investigative work: the importance of ruling out potential suspects. He emphasizes that eliminating individuals from consideration is just as vital as uncovering new leads. This approach ensures that investigators can focus their efforts on the most promising avenues, ultimately leading to more efficient and effective case resolutions.

The idea reflects a meticulous and strategic methodology in criminal investigations. By narrowing down the list of possible culprits, investigators can concentrate their resources and attention where they are most likely to yield results, demonstrating the intricate balance required in solving complex crimes.