Murder anyone?

This may sound cynical but I believe that most of us are capable of murder. The question is how far would the average Joe--not a psychopath or otherwise mentally ill person--have to be pushed in order to actually go through with murdering someone?

I'm asking this question, not because I have any plans to commit murder myself, but because I am writing my first murder mystery. I know that there are some seasoned mystery writers on this blog so it's a great place to look for advice.

I love mysteries. Hercule Poirot was one of my heroes when I was a child and I still love a good mystery to this day. In fact, when I recently read eight young adult murder mysteries in a row to get a feel for what's on the market, it was the best fun I've had in a while...yes, I do need to get out a bit more. :-).

For my mystery, I know the how and the who. I have a line up of suspects to keep things interesting, but the thing that I find most challenging is the why. Money, jealousy, revenge, self-defense, to protect a loved one, and to cover up a secret are some of the more common motives for murder, but despite their problems and their flaws, my characters have not quite convinced me that they would be moved to murder by any one of these factors.

This is probably my pet peeve about murder mysteries. There is nothing I hate more than to find out that the murderer killed to solve a problem that 1. could have been addressed in a much less complicated manner, or 2. remained unsolved even after the murder. I also hate if the murderer is suddenly framed as being crazy despite acting rationally until that final reveal. I do think that in some cases the problem is not the motive, but that the character of the murderer has not been developed sufficiently so the reader believes the motive. But other times the motive is the issue. Would someone risk a lifetime in jail to stop a politician from changing a law that would destroy their business prospects? Would a 'sane' person kill their brother to cover up a thirty-year old secret that would cause a ripple across society at best?

I have it a bit easier writing a YA mystery because teens are notoriously self-centered and more likely to think their problems are a matter of life and death. I don't think that gives me a pass on developing a good motive so I am throwing out the question to you. Dig deep, answer anonymously if you must...just in case... What would move you to commit murder?