Caskey then became senior investigator, Laboratory of Biochemical Genetics (1967–70) and head, Section of Medical Genetics at NHLI (1970–71).
Following his appointment, Caskey took on the role of senior investigator in the Laboratory of Biochemical Genetics from 1967 to 1970, and subsequently became the head of the Section of Medical Genetics at NHLI from 1970 to 1971.