Yes, it is possible to report such a blog that advocates shooting police or members of local government, and I strongly urge you to do so. You may report any such activity to your local law enforcement agency. For the Fort Wayne Police Department, you should call the non-emergency line at 260 427-1222.
I am not well versed on when free speech becomes criminal activity, but as a law enforcement officer, I want to know about a blog/blogger that is advocating for my death or injury. This activity or behavior has the potential to escalate to violence. We have seen too many tragedies recently involving law enforcement officers and members of government. As I am certain you are aware, just last month six people were killed in the shooting rampage in Arizona during an open meeting held by US Representative Gabby Giffords. Later that same month and closer to home, we learned of Indianapolis Police Officer David Moore who was shot in the face during a traffic stop and subsequently died. I believe that if you learn of or come across information that an officer or member of government might be in danger, it is your duty to report it. It seems, by some of the other posts on this topic, that others would agree. And even if we cannot pursue a case or charges, then at the very least we have obtained the information.
Here is an interesting article I read recently in the The Journal Gazette by reporter Rebecca S. Green, Letters lead to Federal Charges:
Thank you for the post.