I don’t think he was murdered.
He was searching on his home computer for topics like how to wipe your hard drive, will water destroy a laptop, etc.
I think he pulled a disappearing act, for reasons best known only to him, and since he’s been declared legally dead (as of this year), I’d say he pulled it off pretty successfully.
Another poster speculated he could be in Slovenia, as he’d traveled there to visit family a few times. It’s possible. It’s not so easy nowadays to disappear, but it can still be done.