I thought OnlineAuthentics was a service that witnessed or conducted signings, but apparently not.
From their site below:
Registration #: OA-8187337
Item Signed By: Michael Jordan
Type of Item Signed: 8 x 10 Photograph
Type of Writing Device: Gold Paint Pen
Origin of Item: Physical Review
Date Item was Signed: Physical Review
Picture of Item: (matches)
Physical Review Service
OnlineAuthentics.com offers a Physical Review program that allows our users to submit items for physical examination by our Review Staff, a group of some of the most knowledgeable and experienced dealers and collectors in the industry.
Many collectors have large collections of signed sports memorabilia and we invite our users to send us items for our Review Staff to evaluate. Once our Review Staff determines an item meets our review parameters we will then issue a numbered letter outlining what the item is as well as our review of the item.