The Serial Killer
Jealousy has been known for its multiple killing sprees since anyone can remember. It is the root cause of every murder. People need to learn to control jealousy towards others. There would be less conflict and problems in society.
Law enforcement always interviews the murder victims' spouse or significant other first in all investigations. People are most likely murdered by the ones who are closer to them. This is a sad thing. Trust means nothing to some people. Then sprouts jealousy, conflict, and sometimes murder.