My only point is that there was sufficient gaps in Michigan's self-defense law that if the police want to charge you, they can probably charge you. Florida's self-defense laws are tougher than Michigan's and look where Zimmerman is at. If the punk ripping you off is the nephew of a City Councilman or influential clergy, you could easily find yourself on the wrong side of jail bars.
If you are faced with the unfortunate situation where you have actually used your weapon you should: (a) never make it sound like it was about property; (b) tell the police officer that you were in fear of your life and felt you had no other choice; (c) try not to have a bad ass tone in your voice; and (d) tell them because of the loss of life/serve injury, etc., you don't want to say anything else until you have a lawyer. Hire a lawyer (by the hour) at this point to do precharge deflection. Have him/her work with you on your statement and send it to the cops. Don't make the mistake of thinking you can handle this yourself. You may pay $1,000 in pretrial deflection, but if you if you are charged you can easily pay $50,000. If it is possible to say something that sounds like you regret taking a life without coming close to admitting fault, you might wish to do so, but be careful, e.g. "he was only a kid." Again, don't make them think you were junior G-Man killing someone over a laptop, a pair of hubcaps, etc.
If you think you are smart enough to talk yourself out of this mess, google on the Reid method of interrogation. Moreover, everything you say will be deemed an admission. Straight logical arguments are the classic example. If someone offers a factually flawed argument and you assume for the sake of argument you were in the positiion they claim and show the flaws fo the argument, I've met too many people who will take your assumption for the sake of argument as an admission of fact.
An attorney can often set the tone, say things on background, etc. to the cop which you can't because it won't come out right or because it will be deemed a party admission. Before you think that only a guilty man needs an attorney, look at most police contracts. They have their own set of Miranda warnings ("Garity rights") built into the contract.