There is something in the serial killer or psychopath world that makes them irresistible for the masses, even though we might consider them despicable, crazy and scary.
These crazy individuals, deluded in their own grandeur aspirations, able to do whatever their ego say without caring about the consequences, are around us. Like them or dislike them, they exist.
Since I studied psychology at high school, I had interest in discovering what make a person believe that acting like that is justified or had any type of sense. As well, the way the police profile, study, research, investigate, arrest and take care of them is something extremely interesting. My end of the course essay was about that, I remember titling it “Psychopathy: what society is exposed to”. The essay wasn’t as good as the headline, but well, I was a 17 years old kid, so I think I did ok.
In my search of interesting books, I found this series, the Robert Hunter by Chris Carter. 
From page one got me hooked, first for the violence of the killer, the gore scenario, the evil and twisted mind behind each serial killer, for the background the writer put us through. At one point, you start thinking if what triggers most of these twisted minds is not the own society and culture we are all living.
Moving back to the books, Chris Carter has created a universe where nothing is good, no character is plain white, they are have so many things to hide, many fears, many issues from the past that need to be resolved but they are too scared to face. You can feel the strength and the vulnerability on them, you feel the tribulations and that’s exactly when the travel begins.
Each novel has a different serial killer, with a different purpose, a different way to act, different triggering issues but all shared one component: they are gruesome and gory. Sometimes the scenes are tough to read but the violence related is not gratuitous, in the bigger picture of the novel, somehow makes sense. 
Overall, the novels are interesting, you see how the characters evolves throughout the story. Chris Carter made the read fun, enjoyable and interesting without giving away many clues.
The books are well researched and you can feel the background of Chris Carter as a psychologist.
If you want a thriller, with many twists, grousume crimes, interesting characters, then, you need to give a try to this series. You won’t be disappointed.
Very recommended series.
ISBN (The Crucifix Killer -1-): 1847376223