Philanthropists : Inspector Mislan and the Executioners by Rozlan Mohd Noor

The cash was stolen but not the drugs.  The cash is given to homes for children that lived on the street.  Who could be doing it?

Arcade Crimewise and Edelweiss let me read this book for review (thank you).  It has been published and you can get a copy now.

As they look for the killers, they find themselves looking for cops.

The killers are could use some therapy but they don't go for it.  

The killers commit suicide.  It's amazing that they would do that.

You won't be bored.  There's plenty of action in the story.