A mortal and friend of Duncan MacLeod's, he is apparently Duncan's go to guy for scientific inquiry. In Deadly Medicine, MacLeod sought his help in the development of film that had been submerged in eighteen feet of salt water. A task Sam managed to accomplish, and then further managed a computer enhancement the final shot on the roll, and then tracked down the meaning of the symbol they discovered on the photographed ring.
In Free Fall, MacLeod enlisted him to authenticate an illuminated map that he had been told was a forgery. Sam confirmed that it was indeed a forgery, but one that had been executed 200 years ago. He assured MacLeod, "I do like a challenge."
