They had a warrant for the raid. Or at least they showed me a piece of paper, but my mind was so thrown that I literally couldn't read it (I've never experienced such a thing before or since - I literally couldn't make out letters on the page, such was my state of shock at the time).

I wasn't arrested or charged, they found nothing of what they were looking for on the multi terabytes of disks they seized. No further action other than the raid.