Ozzie Mitchell owns a few dojos in the East and Southeast, I believe. He also does the lecture/demo circuit, putting on seminars pretty much around the country. You should be aware that many people who have or claim to have 5th, 6th . . . 10th degree black belts have had some honorarily bestowed. Practically speaking, many are meaningless. It is also hard to know what they mean given that different schools/styles have different levels and requirements.
I've taught Tae Kwon Do (different than Ozzie Mitchell's Karate) for over 15 years. However, I have never sought advanced belts past the second degree. I'm not saying I'm better, only that the degree does not always mean skill. It often means politicking within the particular style's governing body. For instance, I think Ozzie Mitchell is involved in the Olympic Training biz for Athens. That alone may have boosted him from 9th to 10th degree (as an honor).
For what it's worth, he seems competent. I wouldn't rank him among the greatest, but he has been an effective teacher/demonstrator. He also seems technically sound.
Did you depose him as an expert, or a fact witness?