I'm just going to let the turtle go!?

If you caught it then its ok and legal to put it back its only ilegal if store bought, and I have a feeling its not since you don't know what type of turtle it is. If its face is orange and red its a box turtle and i don't know about where you live but in missouri they are protected by the law as a endangered species and are considerd rare (although over the course of a week we have caught two and released them, and yes they were diffrent ones).