Someone did exactly the same thing in Hawke's Bay a few years back. They took brood and bees and replaced the frames. Not sure how many hives were affected but it was quite a few and three different beekeepers all had the same problem. I believe the offender was eventually caught and slaped with a wet bus ticket.
Over 40 years ago there was a local character who would take a load of wets out and park on the road beside somebody's apiary until the load was full of bees and then throw a cover over and drive off to one of his own.