He completed his doctoral studies at Cambridge University, United Kingdom, in Clinical Biochemistry under the mentorship of Dr. Margaret (Scottie) Robinson. After completing a Postdoctoral Fellowship at the University of Pennsylvania, Philadelphia, PA, he was a Visiting Professor of Biology at Swarthmore College, Swarthmore, PA, before moving to Georgetown. Theos's cell biology laboratory seeks to answer questions related to the biogenesis of lysosome-related organelles in specialized tissues. To this end, his lab focuses on the very basic molecular events by which soluble and membrane-associated proteins are transported to melanosomes, the pigment granules of mammalian cells. The aberrant functioning of machinery and cargo involved in this fascinating process often leads to human disease.