I have cats here. But before he died I made doubly sure that they would have 0 access to the tank. I have cat proofed it using duct tape and rope (which is all I have). And when I woke up this morning, the tank seemed completely untouched by any external animals i.e the cats. I'm thinking the two turtles got into a fight.... Help please!
They are in a 60 gallon stock tank indoors (can't keep it outside due to lack of necessary supplies to do so and the money to get those supplies as well to keep them outdoors due to there being a myriad of strays (both cats and dogs) as well as coyotes, foxes, etc. Here are pics of the pond:


