And them "putting up a fight" is a second crime, not the theft of property.
And whether or not lethal force is justifiable is where the proportionality comes in. If the thief punches you and runs away, no, you don't get to kill them, legally speaking.
Gonna have to cite your sources, dude.and you're not going to get charged with murder if someone dies as a result of fighting you when they stole your stuff and you tried to take it back... even a man that went out on his porch and shot a 15-year old dead and seriously wounded another got off with manslaughter and aggravated assault and he stayed out of prison as well... they didn't even attack him and he didn't go to prison for it...