Dr. Aldrich is a medical examiner.
When Mr. Xavier mysteriously died, Dr. Aldrich was the one who examined his body. When Sam and Dean arrived at the morgue brandishing CDC badges, she said she didn't believe they were CDC. They were unnerved, until she explained that it was the first time in history the CDC had shown up a day early, not forcing her sit and wait for them. Dean replied that it was a new administration, with a change she could believe in.
Dr. Aldrich pulled Mr. Xavier's corpse from the freezer for them, and he appeared to be a man in his 80s. She told the brothers that Mr. Xavier was born April 3, 1984. The case of such a young man apparently dying of old age confused her, so she had confirmed it by running his DNA twice.
She promptly left the morgue to the CDC agents to complete their inquiry.