Dr. D. Winters was a coroner working for Agent Camp.
For an unknown period of time, Dr. Winters has been employed by Agent Camp to work at Site 94, which he is forced to visit while blindfolded on a daily basis to prevent him from finding out Site 94's location.
In 2017, he is assigned by Agent Camp to check on the corpses of Sam and Dean Winchester, prisoners who have mysteriously been found dead after two months of imprisonment. Dr. Winters is bewildered by the fact that the brothers, despite being in different cells, managed to die on the same day.
When Agent Camp and Rick Sanchez begin arguing over how the prisoners were handled, Dr. Winters leaves the morgue. He returns sometime later to find Sam and Dean alive. The brothers intercept him and demand to know where they are, but Dr. Winters admits he does not know.
When Agent Camp and Rick return, the brothers are gone and Rick discovers they had stuffed Dr. Winters inside one of the morgue drawers. He greets Rick with a "hey".
Unfortunately for Dr. Winters, his involvement with Sam and Dean drives Arthur Ketch to assassinate him as he is now considered a loose end. Every employee, including Agent Camp and Rick, are killed at the prison.