I honestly have no idea. There is no way to know 100%. Speculation would be just that, speculation. I believe it was through lucky7coin wallet, but I have no way to actually know that, that's just what was stated. If I had to make a bet though, I'd honestly bet it was someone outside of the company. That's just my opinion though.
Thank you for your views but it would be hard to believe that one wallet screwed everything up for everyone when cold storage was used... but thank you for your insight