Punishment for elder abuse?

What is your opinion on the punishment one should receive for elder abuse? And do you think the penalty should be less severe for mentally challenged perpetrators?

I am furious with the justice system right now. My mentally challenged alcoholic uncle has been abusing my grandmother for years. He steals her Social Security check every month, and mentally and physically abuses her. We have tried to remove her from the situation, put her up in our home, a safe house, have called the police several times....they always seem to make their way back to eachother.

My uncle was arrested for the up-teenth time the other day for stabbing my grandmother in the leg. She is now in a nursing home, and may need her leg amputated. My uncle spent a total of one night in jail. I don't understand how the authorities can just let him go, time and time again. Do they feel sorry for him because he's mentally challenged? Thoughts?

* 4 minutes ago

People who defraud or hurt any old people should be tied to a post naked in a public square and be beaten with a whip. It is utterly disgusting and unforgiveable. An old person is just as vulnerable as a little child, they are defenceless.