I had to give up on an airplane mystery/thriller series (Jeffrey Deaver/Lincoln Rhyme) (which annoyed me for other reasons) because just about every one of his tales of forensic deduction relied on dragging the plot out by having the killer plant elaborately-falsified or misleading fake trace evidence at multiple crime scenes (can’t have the hero look dumb by missing obvious clues, can’t let the killer get away, so you have to posit a fiendishly clever and forensically-aware master criminal planting all sorts of microscopic red herrings). Annoying as Hell as I’d imagine that the number of times convincing but fake trace evidence has been deliberately planted IRL is, in sum total, less than this one fictional detective encountered in the space of just a couple of years.
Here is an article about Stephen Bryant, who killed four people and left taunting notes to investigators at the scenes of the crimes.
Bob Erler, the Catch Me Killer, called police after claiming to have killed 3 people and asked to be caught, though he did not provide any actual clues and actually only killed one person.
When the police finally crack my code, it will read: “Drink More Ovaltine.”