Steve Carty, Photographer
Cam stats: Camera - Canon 7D. Lens - 85mm 1.8. Exposure - 1/25 @ f/13 ISO 100
The Key light for this portrait looks like it was placed high on the right of the camera and shining down on the subject, which created the shadows on his neck beneath his chin and beneath his nose. It would also explain why the shadows from his glasses seem more cast downwards. I think the light is diffused. The key is creating a nice eyelight in the subjects right eye. The right of the subject was probably lit by a bounce acting as a fill. The top of his head seems like it was probably flagged to keep the key light from illuminating it too much.
There may also be a small light lighting the background to separate the subject from it. Thhe sweater works nicely in contrast against the shirt to also separate the subject from the background.