It looks very much like a Privet owned by either Dustin Mann or Bruce Baker. However; I believe that it was sold a number of years ago. This tree is actually a lot larger than the picture would lead you to believe that it is, if it is the tree I remember from the MABA show in Milwaukee many years ago. Then again I may be totally wrong.
I think that Privet bonsai was owned and displayed by Jack Fried from the Chicago area. It won "Best of Show" a few years ago. A long time ago I think it originally belonged to the late Alex Alexander or Tom Tecza. Alex found it growing on his farm in Mississippi. It's been around for several decades as a bonsai container at this show.