Richard Castle: Looks like she was stabbed with a knife.
Kate Beckett: Mmm.
M.E. Sidney Perlmutter: To the untrained eye, perhaps. But... what you don't know about postmortem analysis could fill a book, Mr. Castle. In fact, it has. Numerous times.
Richard Castle: Fine. So, it was not a knife.
M.E. Sidney Perlmutter: Ah, wrong again. It was a knife, but "stabbed" implies the blade was thrust into the victim, uh, whereas this wound was produced by it being hurled into her chest.
Kate Beckett: What is this, "Last of the Mohicans"? What kind of knife is it?
M.E. Sidney Perlmutter: Uh, one with a hilt that matches these small bruises on either side of the wound. It killed her instantly, severing the left anterior descending artery.
Kate Beckett: Okay, so either that's the luckiest knife toss in the world...
Richard Castle: Or, she was killed by a circus knife-thrower. Like the Great Throwdini.
Kate Beckett: Who put you up to this, Bobby? Who gave you that backpack?
Bobby Lopez: I don't... I don't know. I don't remember.
Kate Beckett: You don't remember? How do you not remember?
Bobby Lopez: I was in shock. A bomb went off, everyone was running and screaming...
Kate Beckett: Oh, oh. Okay, okay. So you remember what happened after the bomb went off but not before?
Bobby Lopez: It must have been one of those traumatic amnesia things.
Kate Beckett: Bobby!... Don't lie to me.
Bobby Lopez: I'm telling you, it was all a big blank. It was the trauma.
Kate Beckett: It was not the trauma. You don't get to use that excuse.
Bobby Lopez: I swear! I don't remember.
Kate Beckett: The *hell* you don't remember! Do you want to know trauma? I was shot in the chest. And I remember every *second* of it... And so do you.
Richard Castle: [watching in the observation room] All this time... You remembered?