What is the most common mental disorder in Serial Killers?

Define this dependent variable and consider how it can be measured. Then look at potential independent variables. You may be able to incorporate data that is out there and propose a secondary data analysis. If you can find meaningful, relevant, existing data you could propose a study that would look to see how certain variables relate in this specific population.

Revise your chosen methodology, design, and data-collection tools as needed. Also, define the process from the selection of participants (and stakeholders as applicable) through data collection to data analysis, including any limitations, delimiters, and assumptions. Include all ethical considerations. Paint a picture of the entire process to show how you will conduct the study.