Well, it's better than nothing. If the family says he was there and the family was united, odds are he was there just as they said. I'm sure there's more than one Christmas that I'm not shown in any of the pictures since I'm the picture taker and avoid the front side of cameras at all costs.
I know what you mean - I avoid cameras, as well. I think the picture might at least somewhat establish where they were that Christmas. I think they would remember if there was a Christmas that they did not spend together, as this is an unusual time to be apart (assuming the family is intact). It seems like the investigators would have tried to establish whether he could have even been in Boulder at the time of the murder before doing anything else. If he wasn't there he didn't do it, though I suppose it is possible that he might know something.
yeah, and Karr seems to be type to avoid the camera, as well....