The woman was tried a second time because the jury hung on the second-degree charge.
The system didn't have a chance to work in this case (not that there's any guarantee it would have). Her daughter told her the guy had raped her, mom confronted him that day, and then shot him eight times, pausing to reload.
I am not saying she should have gotten off. I'm saying that the guy should not have been on the street. Of course, we don't really know if he had any priors, but most crimes are committed by repeat offenders. It would not happen if our politicians and our judicial system would do their jobs instead of blaming "society" for crime, and letting the perps go free.