He's just sitting there on the lawn.
What do I do? He's probably a local, but the front yard! What if he goes for the street!?
His shell is damaged slightly, on one lower side--looks a bit crumpled. Not enough that I suspect damage to the innards, like you'd get from being hit by a car, more just one of the flap edges bent down a bit. Probably just a scar of a hard life. He's just...a turtle. On the lawn.
Update: His shell measures 12 x 8. He is some species of slider--he pulls in whenever I get near, so I can't tell if it's a red-eared or not, but definitely a slider. He can walk under his own power, and so, as far as I'm concerned, can stay in the wild. There is a scuffed place in the lawn where he was sitting, leading me to believe that he either was digging around, or...god help us...maybe it was an impact crater. (Do birds of prey really pick up turtles, or is that just in "Small Gods"?) Regardless, he's fairly mobile. At the moment, he is basking. I am concerned that he may try to make a break for the road, so I'm going to have to move him.
Update Again: Okay, acting on better advice, I'll leave (her?) alone. I'll keep an eye out in case she goes for the street, though.
Jesus. The defective wildlife must have been saving up for this...