Disturbing case involving Developmentally Delayed Adult in West Palm Beach, FL

I've been down in Florida visiting family now for a while.  As a New Yorker, I've been through and seen a lot, but let's just say I think a lot of things need major fixing down here in Florida. 
One thing I've been watching very closely as it has been quite disturbing and is near and dear to my heart, is a case involving a 36 year old Developmentally Disabled young man named Aldo Alvarez.  I do not know the extent of his disability nor do I obviously know the exact events that occurred that day as I was not there.  But just as close as we all watched Treyvon Martin and quickly gathered our opinions of George Zimmerman, I promise you'll do the same here.  Luckily this time, lives were spared, at least for now. 
Aldo had lived in that development for a long time along with his mother Ana.  He had been known by others living in the community to take walks around the gated community, often saying hello to people.  Everyone knew who he was, or at the very least recognized him. 
Deputy McGehee was just moving into the community. On a day early in May, Aldo was on one of his walks and saw Deputy McGehee in his garage unpacking.  This is where the rest of the report becomes peculiar and uncharacteristic.  The Deputy states that Alvarez comes up the driveway and starts beating him (or attacking him out of nowhere). The Deputy decides that he has no choice but to shoot him as even though he's off duty, his gun was all he could reach, and Alvarez was unarmed. Although Alvarez was shot 10 times, he was lucky to live. Alvarez is shot, arrested, and now most recently reported, facing a lifetime prison sentence.  The Alvarez shooting was the only one of four involving sheriff’s deputies that did not result in a fatality. Thankfully he is alive, but the following questions remain: why is Mr. Alvarez facing prison? Why a lifetime prison sentence? Why is the Deputy not penalized for shooting an unarmed person?
I am deeply saddened by the above for many reasons.  This kind of thing constantly goes on all over the state. I would love to hear how everyone else feels.  

If you would like to read more about the case, simply google both names, FL, as there are many articles.