28lb bag is pretty good for the Nick. There have been some huge bags caught, there, recently. Did you get any pics of the cage? The craftsmanship or lack of it, may be a strong clue but only one piece of the puzzle. Was the slough before you hit the river or the one, to the immediate left of the ramp and docks?
This caliber of person or persons, couldn't help but keep an eye on it and may have been watching you as you were messing around it. That would be watching you with binocs because to physically guard an area may lure other fisherman there, thinking there was a bite on.
The person(s) probably fish every day. Their either retired, on disability or work an odd shift, like me. Can you imagine how nervous they would be, not watching it constantly. That's a winning bag and most likely big fish.
How big was the cage/basket? Would it fit in a bass boat....better question, could it be hauled around in a bass boat and not stand out? if it was too big, a pontoon boat would be the hauler and that would mean a person or a pair with a bass boat and access to a pontoon boat.
If it was a pair, they'd almost have to be brothers and very close, almost inseparable. There's almost too much anxiety for it to be more an a single individual because of the chance, one would come clean and blame it all on the other. Never under estimate the power of a conscious. Having said that, if it's a solo, I bet this person would have a stone cold personality....probably smoke.
Also, the fish would have to be put in the live well after being caught. Anyone seeing a big fish being caught and not being thrown back in, during the week, should remember that because it's not the nature of a bass fisherman.
For some reason, I keep picturing someone a little older, maybe a fading star. I think the younger anglers believe they can win with time on the lake but things like this will have a corrupting effect, even if, just a little. It's one of those, end of the innocence moments and I just realized, that's the worst part.
That's my profile of this person or persons and I have absolutely, no one in mind.
It's sad but but it gives all those honest fisherman that have caught good or winning bags a bit of a black eye. I don't think it's all about the money, a lot of people that cheat, do it for the rush or excitement.
If there are small waterproof tracking devices, it might be good for each TWRA officer, to have one. BTW, if you're the one and you're reading this: fu, you sorry pos, you've made waste way too much of my fishing time on your sorry ass