One of the potential CA species being considered is S. cyanescens. Dennis Haines (via personal communication) has kindly corroborated that the specimens of this species which he has access to "have a distinct blue cast to them" (as one might expect!). All of the images that I took of this beetle on the white background show it looking pretty black, but sometimes this type of contrasty scenario can cause the exposure/color to be slightly off. For the sake of speculation, I've added this shot showing the beetle in the shade on the ground where I first found it.

Please see comments on initial linked image.