Thinking further on this in the shower.
◈ The Femme Fatale trope. It could be a reverse, with Herrera being the fatale.
◈ The book opens with a "quote" of "Fuck the cops."
◈ Herrera was a cop who quit under as of yet untold reasons.
◈ The Detective insisting on deadnaming Kiera.
◈ Herrera refusing to call the detective by what they want.
◈ I don't remember if Herrera ever calls Kiera by name.
◈ Mal quit before Herrera, and their leaving the force is somehow related.
◈ Kiera's dead friend from before the book is somehow involved in the plot.
◈ Herrera uses the dead friend's first name as an alibi.
◈ The detictive mentioning that 'people's natures rarely change'.
◈ I had something on his mentioning the buddhist concept of emptiness, but I forget atm.
◈ Herrera's hidy-hole for Kiera is a buddah hologram.
◈ The killer's calling card is incense.
◈ The one-eyed guy looking sad for Kiera, he know more than he's letting on in multiple ways.
◈ With Herrera's new hand, I'm suspicious of how much of a luddite he is.
My current speculation:
Herrera is a transphobe. He somehow knew Kiera's dead friend. During Kiera's relationship with them, the friend came out at trans. Herrera kills friend, but blames Kiera for "changing him" or some shit. Mal figures out it was Herrera, but when he brings it up, the cops cover it up. Mal quits over this. Herrera ends up quitting over something related and blames Mal and Kiera for that too. This is all a plot to get revenge on Mal and Kiera, killing Mal and blaming Kiera, possibly getting her killed by the cops.
Niel fits in somehow too. Either they're innocent, or an undercover cop helping Herrera. In that case the hand was the one they already had replaced. The other actors have been paid/coerced by Herrera, one-eye and the person with the trick voicebox doing the unseen characters.
If this is the case, the plot might go sideways and Herrera ends up trying to outright kill Kiera, as those with antagonistic schemes rarely get away with it in code-era Noir.
~
I could be 100% off track, but that's where my head is at the moment.
