When a member dies...and their private messages?
Using Jamroom
Its really up to you how you handle this, but personally, I'd suggest that unless there was a very good reason, his private messages ought to stay private, so to achieve that, clone his quota to a 'Memorialised Quota', disable the PrivateNote module for that quota, then move him to it. You would also then have the option of testing for the quota in the profile templates and adding 'Memorialised' next to his name, say.
I'd also set his profile to one of the 'followers only' options and certainly set the 'approve followers' option. I wouldn't give his user account to anyone (unless there was a very good reason, of course) and I'd even consider deleting it, leaving the profile owned by master admin (you), but if not, certainly change his password, just in case anyone else has it.
hth