But really, it wouldn't surprise me that Karpeles bought Silk Road early on from Ulbricht. When the feds seized dollars from Gox (~July 2013), he knew he was in trouble, being watched, so he went back to Ulbricht, and said "you take S/R. Here are some coins, here's the site." and he transferred Silk Road and a shitload of Gox/SR coins to Ulbricht's custody.
And then when Ulbricht got busted (Oct 2013), the ton of bitcoins were confiscated by the US Marshals. If those were Gox's "cold" storage, mixed with some Silk Road stuff, that would explain where the lost Gox coins went.
At that point, Karpels is scrambling with his Gox business, trying to hold things together, with zero reserve. He writes a bot (willy), to buy bitcoins regularly, in an effort to try to even things up (since he now has people's fiat deposits, but not enough bitcoins). Gox makes money on every transaction, so pumping volume is a good thing. And it gives him a chance to get his bitcoin balance closer to what it needs to be at considering everyone's deposits.
But this plan fails, because the price is rising (and willy isn't helping!). So, things get out of hand - he's actually getting into a bigger hole, because he's depleting his cash by over-paying. He hasn't thought this out.
So at this point, his cash reserves are totally under-funded, and his bitcoin reserves are under-funded. So he starts delaying withdraws.
And then he finally gives up. Blames it all on transaction malleability. There's nothing left. No fiat. No Bitcoins. (it's weird that few people have really questioned where all the fiat went from Gox.)
Karpels knows ultimately he's going to be murdered or go to jail for a long time (or both), so he takes his personal stash (200K BTC) and "finds them" for Gox. (He has subsequently claimed publicly that these were his personal coins, or so I hear.)
Now he sits, waiting for the shoe to drop.
He is fortunate that he was able to hang the DPR stuff on Ulbricht, because it's likely he'll escape that charge, and Ulbricht may actually be able to cast some doubt as to who is DPR, given the ever-changing role of DPR - multiple people, handed off several times, etc. But his day is coming.
Well this would explain his unwillingness to travel to the US. However I don't get how he would have gotten Ross to log into the SR admin panel the day he was arrested.
Several people have been linked to Silk Road via the blockchain only to have the link debunked by the fact that they happened to sell their bitcoin on Gox. This would explain why so many people on silk road were selling on gox