Dutch and Billings in “Unfinished Business”

Dutch

He stood there and watched somebody die like it was nothing. There's speculation Bundy's first murders were committed in his early teens. They gain reinforcement the more crimes they get away with. Gain power, their methods improve.

Billings

Wait a minute. I buy the setup theory. But you're saying this kid's a serial killer?

Dutch

They all pop their cherry somewhere.