Did Grindelwald create a Horcrux?

[verosomm]

No: HPFGUIDX 170979

I'm much more of a lurker than a poster, so I hope I'm doing this right.

And I'm sure this has been covered before, but doing a search of "Grindelwald horcurx" 
didn't yield exactly the responses I was looking for, and of course, just caused more 
questions!  :)  

My main question is if there is "canon" to back up some theories that are v.v. old, some of 
them probably going back to PS/SS.  I have no problems with theories and am actually 
going to be a little sad when DH comes out that there are no more theories!  But some of 
these older theories now seem to be stated as fact, which is where my confusion comes in.

I'm wondering if we know (or have a good idea) that Grindelwald created a horcrux... 
someone mentioned on here that one other wizard has created one... did JKR say that 
someone other than VD had created one?  If so, I think the assumption that it was 
Grindelwald would be correct.

Also, are we to assume that Riddle and Crindy had some sort of connection, as Riddle left 
Hogwarts in 1945 and DD defeated Grindy that same year?  My guess is that Grindy taught 
Riddle how to perform the horcrux spell before DD defeated him, as Sluggy didn't know 
the spell itself, and that the reason VD has only ever feared DD is because he's the only 
wizard VD knows of that knows how to destory a horcrux (although I definitely believe that 
each horcrux must be destroyed differently).

Finally, was there something said by JKR that confirmed that wizards and muggles worked 
together to end the Muggle WW 2?  I read that somewhere on this list as well, I believe, but 
again, can't find any JKR confirmation on that fact.

Thanks!

Veronica