Chapter 4x01 - Scarlet Ribbons, approximately at minute 22.

Patrick Jane visits Timothy Carter's home. They go to the back door, and just before meeting Charlene Carter, the camera shows some guests in the living room - a memorial to Timothy Carter is about to start -  behind the glass of the door.

The man facing the camera on the left side... isn't he Sean Barlow?

I cannot watch the series in HD, but I would say he is. Could anyone confirm this with HD image?