Why has the chief of Criterion Capital Partners bought Poolworks, as the firm is known these days? Good question. And the whole story of why it’s taken this long to confirm the identity of the new owner is just plain weird.

Let’s take a deep breath…

Back in June, VZ Networks – the ailing proprietor of Facebook clone StudiVZ and other networks aimed at various demographics – rebranded as Poolworks and announced it would be focusing on its school-age system SchülerVZ, also rebranded as IDPool. (That new site is still only a ‘coming-soon’ affair.)

Then, in September, Poolworks owner Holtzbrinck Ventures surprised everyone by selling the company to the ‘international investment organization’ Vert Capital. You know, Vert? No, me neither. Anyway, Poolworks CEO Stefanie Waehlert was out and almost everything went to Vert, with Holtzbrinck retaining the option of ‘using’ SchülerVZ/IDPool.

Bebo was rumored to be behind Vert, but no-one would confirm it. Meanwhile, nailing down an online presence for Vert – or indeed any references to the company – proved to be very tricky. Then Der Spiegel reported that Levin was the mystery buyer, saying he had kept his identity secret because of an ongoing lawsuit against Bebo by Walker Digital over in the U.S.

That would be the same lawsuit (PDF) in which two patents, supposedly covering functionality such as privacy settings, were asserted against co-defendants Facebook, Google, LinkedIn and MySpace. If this really was a factor, Levin presumably thought Walker Digital would try pulling his new property into the suit if it found out he’d bought it.

All of which brings us to today. Walker Digital must have ended its suit, or be about to, because Levin has finally gone public, in a way. As the eagle-eyed folks over at Deutsche Startups have spotted, the Poolworks properties now list as their authorized representatives Adam Levin, Joseph Nejman and Mike Pope.

At least two of these guys are Criterion Capital men – Levin’s the MD and Pope’s the CFO. So what the heck is going on?

“Vert Capital is its own entity and Criterion is a separate entity,” the spokesman who handled the original announcement of the Poolworks takeover told me on Friday. “People were saying Bebo bought this, but Bebo did not purchase VZ Networks. There’s overlap in terms of personnel, but there are two different capital structures, two different sets of investors.”

“Now, will they look at any kind of synergies based on the fact that Adam owns stakes in both? Perhaps, but at the time it was very much overblown.”

So, does Vert Capital have any other activities, apart from running Poolworks/VZ Networks? “A few”, apparently, and we should look out for announcements of those “shortly”.

I have a feeling we’ve not heard the last of this tale. Here are my outstanding questions:

• Was the patent suit really the reason for all this secrecy?
• Are the Poolworks properties going to be merged with Bebo?
• And last but not least, what on earth is happening with Bebo anyway? Seriously, the last thing coming out of Bebo that I can find is a post thanking fans for generating 100,000 likes on, um, the site’s Facebook page.

StudiVZ was bought out by Holtzbrinck group, the German publishing giant, for a reported $112 million (IHT says the price was around $134 million, but both numbers were speculations) late in 2006, and the parent wanted many times that reported price. The two companies surely had talks, but one Facebook source IHT quotes says that those were more related to the issue of copying the design. Since Holtzbrinck bought StudiVZ, it has expanded, starting a new portal in February 2007 for middle and high school students called SchulerVZ, and this year added a portal for college graduates called MeinVZ.

With Facebook’s latest redesign, I guess the similarities are less now, though would be interesting to see if other Facebook clones follow.