Oh, I didn't make the connection that the blonde was the wife of the cop. Anyway, what happened was that they tracked her down at the last victim's house and while they (from outside) had her distracted, Morgan got the would-be victim out the bedroom window. The unsub flipped out and then walked outside holding a gun. The cops and agents were all there warning her to drop the gun and she looked up and said "I'm coming for you baby" and aimed her weapon at the cops forcing them to shoot and kill her. (Suicide by Cop is the common term for this) When the agents walked over to her body, they saw the same markings on her which meant that when she couldn't kill the other girl, she had to use herself to complete his "collection". She marked herself before she came outside and then forced the cops to kill her. Hotch then told everyone that he shouldn't be flying (he got a really bad attack of the ringing thing when the guns went off) and that he would be driving the 7 hours back to Quantico. Rossi told him there's some nice country on that drive and recommended that he extend the drive a day or 2. (In other words, "Hotch. TAKE A BREAK!!!")
I really enjoyed this episode. My 2 favorite parts:
Morgan: (or was it Hotch) What do you need to decode?
Reid: The ability to clone myself and a year's supply of Aderall (this is a nervous system stimulant. It's used to treat Narcalepsy and ADHD)
Favorite part #2: After Reid is rattling off what he's decoded so far and how, Prentiss gazes at him and then pokes him in the face.
Prentiss: He's so life-like. I loved that.