Sad story

[Bogertophis]

That's terrible.
If you have 4 boas like those and you can't keep them anymore I doubt you're going to freeze them to death. The owner would know the value of them, either to sale them or give them out for free if you're really desperate to get rid of them.
Something seems off here.

Yeah, that makes me think they were stolen & then the thief discovered it was too hard to sell them*, or they were afraid of them, or something? *If stolen, it might have been publicized to the extent that the thief knew they'd be caught trying to sell them. Just speculation...it doesn't make it any less tragic though.
It also could have been a deliberate act resulting from a dispute, with someone trying to punish the snake's rightful owner...something stupid, like a pay-back for
a drug deal gone wrong or something. Poor snakes.