My personal opinion of "Monster" by burliAileen was abused by society and life - that's the main focus of the film. There was a reason they showed her trying to get a life, find a job, but truth is: Even if you try to become a straight person, even if you are willing to find a job and get a life, it seems, there is no chance at a certain point. This society is solving problems by executing a "bad person" rather than becoming empathetic for a human beeing and their history. It's easy to say that it was wrong what she did and to simply kill her. And what she did was wrong, yes, but society, her parents and her experiences in life made her become a "Monster". It is the whole point of the movie in my opinion: Society can grow monsters.
In my opinion, the reason she did murder these men was because of the character Christina Ricci was playing so excellent. She did it all for her since for the first time she felt like she was able to care for someone, to protect the aspects in life that are beautiful and harmless. She found love in this relationship and this feeling was so strong that she did everything not to loose it again.
If a person does horrible things like Aileen did than you need to ask why. We are living in 2007, we read lots of books, we have a proper education, we have scientists, we have psychologists, we have therapies, we have realized that there is always a reason why people do bad things. We should at least try to use some of the psychologic knowledge instead of executing people that we do not want in our society because they did something wrong in our point of view. You know, most of us live a good life, we have a job, a family, a house with garden (I know that's clichee but you can probably guess what I try to say with that) - we cannot imagine how we would feel when we had a life like Aileen had. She murdered because she was fighting for love and for a good life - there are soldiers killing children and innocent people in war and noone even knows about it.
You could say that there are other persons who had a similar life to Aileen but did not harm anyone. But that's because everyone's different. I know this is still hard to understand for most people even today: but it is a fact. When we are children we do not realize that it hurts someone else when we harm him/her. The simple reason for that: It does not hurt you if you hurt someone else. By growing older you suddenly realize that others feel similar to you and that you are not the only real person living in this world. All other persons also have a personality like you do, they also have feelings that you have. But that's not quite right: It's not enough to understand that others feel like you do. Because they do not. The might feel different than you!
So the real challenge is to realize that they have feelings like you do, but that they are all different and depend on their individual personality. So you need to find out first, who you have in front of you. It's not that easy to say: Ok, when I was child I was not aware of the feelings of other human-beeings, but now I am an adult, I am mature and wise, I know that they feel like me. WRONG!