The irritating part is that the evidence should be lined up already for the authorities.
Zimmerman has to have some official report on his injuries (if any) on file. Was he treated? By who?
The eyewitnesses to Zimmerman being attacked are unknown to us, but they have to be known to the authorities, if not already sat down for affidavits.
There must have been forensic examination of everything involved.
Somebody has to have all the critical data. What's the holdup?