Hill said he won't convene a grand jury to review the shooting, saying the officers "acted reasonably in their conduct." The police department said Tripp and Skipper remain on paid administrative leave while an internal investigation is being completed.
State police are still investigating whom Bair talked to on his cellphone shortly before the shootings, saying that person could provide information about his state of mind.
"But it does appear that he did have some fixations with mass murder situations and some antisocial behavior," Hill said.
Hill said Bair did have a suicide note on him, which contained short statements about some people he knew, saying one statement was about his mother and the support she gave him and others used vulgar terms for those he thought were against him.
He also texted his mother before the shootings asking if she was going to be at the store.
Hill said Bair got the .40-caliber handgun from a friend in what appears to be a legal transaction.
Bair said a man who called 911 and a store employee who ran when Bair ordered her to stop and then called out warnings about the gunman to those inside the store were unsung heroes.
"Those things have as much with saving lives as anything else," he said. "We were very fortunate that this wasn't a worse situation than it was. As bad as it was, it could have been a great deal worse."