A bit more info on how they caught 'Alpha02' with his computer open that I have not seen on Reddit.
"The security forces caused the server to shutdown. This forced Cazes to access the AlphaBay forums to reply to upset users. Additionally he was forced to access the servers to attempt to reboot them to bring them back online."
Source:
https://blog.comae.io/dark-net-trap-545ae5dd8476
LE timed the raid for when they knew he would be online with his computer unencrypted.
I am thinking the Canadian RCMP, pulled a plug on a server or something similar just before the raid to make sure he would be at his computer trying to fix the site when the Thai police raided him.
Edit: Does this mean they located the server but could not access it?
Those Thai ladyboys got him good.