Mac Taylor and Sheldon Hawkes in “Exit Strategy”

Mac Taylor

We processed this thing when the crime occurred and we never got a second donor. Why would it be different now?

Sheldon Hawkes

Well, I used a different genetic analyzer. Every instrument varies in sensitivity. If I ran it through a third one might not pick it up but this one did. Machines. Sometimes there's no rational explanation for why they do what they do.