Did you ask why? I did. Some reasons are counterintuitive and others are fixable. Yet, here we are.
Possible Top 3 reasons:
1. Collapse of Community Trust and Witness Cooperation
2. Understaffed and Overburdened Homicide Units
3. Shift in the Nature of Homicide (More Random, Gun-Based, Stranger Violence)
And just like counting cards and blackjack, you can turn the odds in your favor by using common sense and knowing a thing or two about how they're investigated.
This is all in fun of course. I don't want to kill anybody.