Mind of a Murderer

What is the biological explanation for why people exhibit violent behavior?

From the video, "Mind of the Murderer," it states several interesting factors that trigger the biological explanations for why people exhibit violent behavior obliviously. Crime, what makes them different? We can say that murderers are distinguished between two types of different sources. An natural murderer, or a nurtured murderer. However, most say a nurtured murderer. Murderers are made not born.
In the frontal lobe, it provides the judgment for the people to judge on the situation.
In the research, scars on the murderers showed the corrugating evidence found. This shows the torture, which establishes the the history of abuse of one's life. This will trigger crucial events with additional mental illness. Researchers say that these ideas comes and go, however the trialed people are sympathetic from the trials and abused experiences.
These people do not think about the future, and their brain are suitable for options for unappropriated behaviors. For example, will it be punishment or reward for their behaviors are never imaged in their brains.
Overall, brain damage is said to be shown from insanity, and early experiences.
One example of this was, Shawcross. He killed all his family, and this was from his peculiar childhood with special distinguished personalities. He was suffering from unspeakable abuse, and this caused his motivation of being a crucial murderer.