What about the Thomas Moore Law Center that Jeb requested guidance on this issue? They wrote him back and provided evidence that he did have the authority.
He says he does not.
I believe that opinion was written BEFORE the order from Greer.
Here's something just up on Newsmax. It says Jeb would have the authority to act in a criminal investigation.
http://newsmax.com/archives/articles/2005/3/25/151900.shtml
Certainly not everyone thinks Jeb did all he could.