“I’m going to stab you to death the next time you come in here,” the prisoner growled.

Nathan feels a lot safer these days. He sees up to 16 patients a day from a suburban Houston office here, using an audio console, a camera and a monitor to treat inmates at two state prisons — including one with a death row — at least 30 miles from where he sits. He’s still threatened occasionally, but now it’s from a comforting distance. Needless to say, he’s a big fan of telemedicine.