His name is Michael Williams, a graduate of TCOM who completed his general surgery residency at Dallas Methodist. He also was a chief anesthesiology resident at Parkland.
Williams has told TCOM students that he considers himself a DO and he's counted as such by the Texas Medical Board (which is headed by a DO and another TCOM graduate). Williams said he basically bought his MD degree from Ross because he felt it might be useful to counter the discriminatory practices at certain hospitals at the time and he wasn't sure where he might end up. This was in the bad old days before the laws were changed.
Incidentally, Williams also holds a master's degree from Harvard and an MBA from Duke. U.S. News named him one of the top medical executives in the U.S.:
http://usnewshospitaloftomorrow.com/press-release-april-4-2013/
Williams is actually the president of UNTHSC. The dean of TCOM is Don Peska, a thoracic/vascular surgeon who got his DO from Des Moines.