Shame on the DA and the police for even arresting this man!
When all the witnesses tell you it was self-defense, then just write the report and let the guy go home.
Doesn't happen that way. Worst thing in the world is an 'eyewitness', especially a number of them. No one sees the same thing, and all views are different and some conflict.
The police, coming on a shooting scene are going to cuff and hold everyone involved until the physical evidence can be determined, examined and a decision made by the DA.