In the end, David McCallum wasn't just a perfect fit for his role as Donald "Ducky" Mallard on "NCIS" because of his demeanor, but because he was willing to do what was necessary to embody his character's level of expertise. Not only that, but he actually enjoyed his first-hand experience learning about autopsies. "It's the most exciting and astonishing," he told CNN in 2009. "It's two hours of learning more about the human body and what a miraculous business it is than you could ever imagine. It is quite extraordinary."
McCallum spoke similarly to RadioTimes, saying, "So for two and a half hours he [the coroner] basically took someone apart, and showed me everything. I watched every detail and I saw exactly how the human body works. It's quite miraculous; it was one of the most exciting days of my life." Aside from examining the innards and workings of actual human bodies, CNN said McCallum also "immersed himself in the subject of pathology" and pored through "extensive reading materials."
When McCallum first got his role, as he told CNN, he immediately took to his bowtie-wearing character. "It was love at first sight," he said. The only problem was he "knew nothing about pathology." But after doing such an excellent job portraying Ducky's medical expertise, RadioTimes says that McCallum himself often got approached and thanked by grateful pathologists.