Do you know anyone that has murdered someone and didnt get convicted?

My friend's mom shot and killed her husband (my friends father). I guess they were fighting about her seeing another man. The fight escaladed quickly and she shot him. She never went to prison. I suppose it was chalked up as self defence. I've met her once, she seems nice. And my friend has lived with her the last 11 years or so. Just a normal person that happened to kill someone