character research

For the last few weeks I have been focusing on getting several story ideas down and seeing how they all pan out. The main one i have been focusing on is one involving a serial killer as the villian, and a cop as the hero.
I have briefly mapped out a story for the characters (which i will present to both my mentors shortly and get their opinions) and started mapping out a suitable background for both the characters. I have researched psychotic killers and serial killers both male and female so I can build up a better understanding of what makes a person act that way.
Currently this is the story I am hoping to run with once I get the feedback from my tutors.
I have taken into account the feedback i received from the online survey and tailored the creation of my charcaters and story accordenly.