>> fassbender says dassey described a brutal scene.een afternoon, his uncle asked him to come over to his trailer. dassey said they each sexually assaulted teresa in avery's bedroom. and avery later shot her in his garage, burning her body in the bonfire. >> it's a game-changer. he told us stuff we weren't really aware of, like teresa was shot in the garage and had died there. >> and after speaking about dassey, fassbender had his team return to the avery property once more. and they found this in his garage, a bullet fragment. and that was missed the first time around. >> well, i guess i could say it was missed. but you're talking about a bullet fragment, looks like a piece of dirt probably. >> and it was tested? >> it was tested. yes, teresa's dna was on that bullet. the bullet was shot from steven's rifle, the one above his bed. >> and do you now believe that teresa was shot in that garage? >> yes. >> one strange thing, though, when they searched the garage for blood, they never found a drop. how could you clean up all that blood? >