and you'll simply be in prison for murdering someone over a phone. it be your word against a dead unarmed person. If they are armed then you'll likely be fine short of shooting them in the back as they leave and being caught on camera. But good luck if you kill an unarmed person. Lawyer up and be rich.
You have no clue what you're talking about.
For starters, you should probably look up with the definition of "murder" is, that would help you in understanding how idiotic your response sounds. The fact that you made the comment about being charged with murder removes any credibility you have with the subject.
You should then understand the meaning of robbery (which mugging is a type of). Now within that, you have two types...robbery by intimidation and robbing by violence. Obviously we're talking about robbing by violence, if you are robbed by intimidation, you are probably not carrying a firearm in the first place.
Afterwards, you should familiarize yourself with the protocol of using deadly force to stop someone who presents a threat to you. A person attempting to mug me would be presenting a legitimate threat of severe bodily harm or death if they actually try to take my phone (or wallet, or watch, or whatever)...If they walk up to me and ask for it, I'm going to laugh at them and keep walking, if they attempt to physically take it, they are stepping into a realm where you have no CLUE what their highest level of response will be to defense, therefore a legitimate fear of severe bodily harm or death is certainly present.
You can call it what you want...preparedness, paranoia, etc...it is what it is. If you decide to take something that is mine by force, you COULD pay for that decision with your life.
Now you keep making the point of shooting someone while they are running away, one situation where your argument against using deadly force stands valid, and any person who carries a firearm legally would know this. But what about the other 999,999,999 situations where the person doesn't just grab and run the other direction? What about when they reveal they have a knife? or a billy club? or decide they want to chop you in the throat? I could list other situations for days that would present a lawful situation for using deadly force...you've listed one. The ratio is a bit lop sided don't you think?
Now please stop talking about your google understanding about law and procedure here with me, i assure you, i know more than you do about said laws and procedure.