Welcome to SR.
Yes, alcohol can cause these behaviors as it alters the brain.
Alcoholism is FAMILY disease, and the FAMILY can contribute to this pattern by shielding the alcoholic from the real consequences of their behaviors.
Who else would you allow to punch you in the face, threaten to kill you, allow to strike your mother, AND NOT REPORT TO THE POLICE? You see, because he is a FAMILY member, the FAMILY is trying to shield him from otherwise criminal acts.
So unless something changes, things will get worse. Because alcoholism is progressive, both for the alcoholic, and for the family around the alcoholic that is shielding them from natural consequences.
This is NOT to say the family is to blame for his drinking. That is HIS and HIS responsibility alone.
The family's responsibility is to determine, and uphold, what is acceptable behavior in your household.
Your mother needs protection. You are NOT protecting her by NOT reporting your violent brother to police. Please know this. Again, this is not to blame, but to provide perspective that alcoholism is a FAMILY disease.
Others will be along shortly with more support.
CLMI