If the owner of the tortoise was contacted by someone demanding money for its return, isn't that extortion? Isn't that a crime, even today?

If someone stole my dog and then offered to return her for cash, I would call the sheriff's department and ask if they would tag along for the payoff. Would they do it for a dog? Probably not. Would they do it for a Lamborghini or Ferrari?

Am I allowed to protect myself from an extortionist when the police refuse to do so?

Sue