5 Criminal Minds Facts You Might Not Have Known - "To Bear Witness"

The episode's opening run around D.C. was actually filmed at the Huntington library. The library houses a number of famous pieces, like Thomas Gainsborough's "The Blue Boy" and two quartos of "Hamlet."

Reid and Blake share a love of crossword puzzles in the episode. Will Shortz, crossword puzzle editor for the "New York Times," stated that his favorite clue for "spiral staircase" was: "It might turn into a different story."

The UnSub conducted crude lobotomies on his victims-- fitting them with intraocular cameras. Researchers at the University of Southern California have been exploring the effects of an intraocular camera system on vision restoration. A blind subject fitted with the system recently recorded visual acuity at 20/1260.

The UnSub's dour lobotomy practices fall into a long history of such experimental procedures. Dr. Walter Freeman and James W. Watts performed a prefrontal lobotomy on Rosemary Kennedy, the sister of President John F. Kennedy, which left her permanently incapacitated.

David Anders, who plays Anton, is best known for his roles on “Alias” and “Heroes.” He frequently depicts characters from Europe, but Anders was actually born in Grants Pass, Oregon.

Watch the full episode with Sync for more behind the scenes here!