DUCKY: The language of silence may be hard to hear, Caitlin, but unlike the living, when the dead speak they do not lie.
NCIS, Season 2, Episode 2 - “Lt Jane Doe”
(Last night I watched the first few episodes of the serial “King of the Rocket Men”. I only mention it because one of the main characters was a Dr Mallard! Unlike his 1940s namesake, Ducky doesn’t have a secret laboratory hidden in a cave, but he is the centre of this episode when he investigates a murder similar to an unsolved case he worked on ten years earlier.)
Quick reminder: when Eric Beale was sent on his first ever field trip (2x21 Rocket Man) he asked Hetty if he had to bring a gun because he didn’t think he could actually kill someone. And he was right. He was left traumatized when he had to do it (season 8, air strike and shooting).