Chances aren't bad that someone did, even if the "pet" they bought isn't a large carnivore.
Um why would their pet eat them?
Because they die, and their "pet" is trapped and starving...for one.
When owners die, some pets eat them for food if there is nothing else to eat. Rodents have been known to go this. Dogs will too.
Like slightly used dog food
How often do you think that happens?