Whomever was trying to make his disappearance/murder look like suicide. Sorry to be vague, but I'm not sure.
Had he walked away and started a new life, with new technology and tools LE has today, he probably would have been identified/found.
The detailed descriptions of witnesses who saw him parked and walking around near the Packwood House Museum make it sound like he was waiting and looking for someone.
Street view of Packwood House Museum
Find local businesses, view maps and get driving directions in Google Maps.
www.google.com
PennLive Map of Lewisburg, PA and locations where Ray was seen and where his car was found.
Key locations that were part of the investigation into the disappearance of Centre County District Attorney Ray Gricar.
www.google.com
Both of those witnesses, who worked for the museum, were very credible and consistent. The red Mini Cooper was a distinctive car and there weren't many around.
Some have speculated that Ray was still investigating the Jerry Sandusky case and was possibly meeting with other witnesses in that case. He handled a lot of cases over the years, though.