They Are All Monsters by J. Boote

 J. Boote can write a horrifying and evil story. While there are plenty of barbaric killings in this book, there is a story to it all. A psychological tale of how people can be monsters, this book focuses on childhood trauma and how the victims become the prey. 

This is a brutal story of two serial killers who have different reasons for killing and begin working against each other. As the story progresses, the killing style progresses. The police are doing everything they can to stop the two killers, but neither one leaves clues to find them and end the savage killings. 

I would seriously check trigger warnings with this book. While it was difficult to read at times, it did have a sad story underneath the cold-blooded killing.