1. Gordon Lightfoot - Sundown: Sets a melancholic, slightly suspenseful tone fitting for a murder mystery's intro or a reflective moment.

2. Prince - Little Red Corvette: Adds a touch of unexpected energy and intrigue. The song's suggestive lyrics could subtly hint at hidden desires or secrets within the narrative. Its upbeat tempo provides contrast to the overall mood.

3. Bob Seger - Roll Me Away: The song's bluesy feel and lyrics about regret and longing could underscore a character's internal conflict or the weight of a past event relevant to the mystery.

4. Bob Dylan - Knocking on Heaven's Door: A classic choice for a scene depicting death or impending doom. Its somber melody and lyrics perfectly capture the gravity of a murder.

5. The Doors - Light My Fire: The psychedelic rock vibe and intense energy could be used to represent a moment of heightened tension or a pivotal scene in the mystery. The song's dark undertones fit the genre.

6. Donovan - Atlantis: This folk-rock track offers a mystical and atmospheric backdrop, suitable for scenes set in the Idaho wilderness or moments of reflection and foreshadowing.

7. Simon & Garfunkel - April Come She Will: The gentle, melancholic melody creates a sense of longing and perhaps lost innocence, fitting for a flashback scene or a character's internal struggle.

8. Kool & the Gang - Hollywood Swinging: This track provides a surprising contrast, injecting a bit of unexpected, almost ironic energy. It could be used to represent a deceptive facade or a scene where characters are putting on a show.

9. Dexys Midnight Runners - Come On Eileen: The song's driving rhythm and slightly melancholic lyrics could accompany a chase scene or a moment of desperation. The unexpected energy again provides contrast.

Expanding the Playlist: To create a more comprehensive playlist, consider adding tracks that evoke the specific Idaho setting. Search for songs with references to nature, mountains, or small-town life from the 60s, 70s, and 80s. Look for artists associated with the folk, country, or Americana genres, which would complement the existing selections. Consider instrumental pieces to provide transitions between scenes or to build suspense. The key is to create a dynamic mix of moods and tempos that reflect the ebb and flow of a murder mystery narrative. Remember to consider the pacing of the mystery when sequencing the songs.