His name is Doctor Richard Carmona, a seemingly competent CUNY graduate of Puerto Rican descent. He resigned in 2006 and I don't recall him ever giving a reason. His replacement is pending confirmation.
Today, testifying before Henry Waxman's House Committee on Oversight and Government Reform, Dr. Carmona explained that he was often silenced by the Bush administration.
His full testimony can be read here.
Dr. Carmona was not allowed to publicly express his opinion on stem cell research, contraception, or his critical opinion of the federal program to promote abstinence to both teenagers and some adults in their 20's.
This is just one more example of what the young and distinguished journalist, Chris Mooney, describes as the Republican War on Science. I'm about 2/3 through his comprehensive book, and while it is not the easiest read, it clearly outlines how Republicans have been attacking scientists for political reasons over the last 20 years.
Here is the video courtesy of NancyPelosi: