So: at the Harvard lab, Walter and Astrid unzip the body bag and befoul the air with a "remarkably pungent stench," notes Walter (who is something of an expert on this score) so Astrid decides to go get some scented candles. Broyles has showed up to check on Walter, because Dr. Sumner called him after his evaluation with some concerns: "He thought you seemed unusually agitated by something you were reluctant to confide," says Broyles. Walter unconvincingly says he doesn't know what gave Sumner that impression, unconvincing because in the middle of him saying that, we were Peter's disembodied voice saying, "Walter?"
Walter asks where the second body is, and Broyles says it's on the way to the morgue, since he assumed one was enough for his examination. This throws Walter into a tizzy, since he says he needs both bodies, but he tries to explain this to Broyles while Peter's voice buzzes around saying, "Walter, do you see me? Walter, I can hear you." The lesson: even when ninety-nine percent erased from existence, Peter is still really annoying.
Astrid's back now, in time to see a complete meltdown, with Walter clapping his hands on his ears, trying to block out Peter saying, "I'm scared. I want to come home." As far as this case, he wants to study the decomposition of both bodies, to help him determine if there's a pattern, if the boys died at different intervals. All of this is tough to take in when Walter eventually screams, "I am not losing my mind!" Astrid and Broyles are staring at him -- Astrid's arms full of scented candles -- and Peter's voice appears to stop, and Walter quietly says he would appreciate Broyles arranging to have the second body sent to the lab as soon as possible.
Walter shuffles off while Broyles takes a call from Olivia, who says they have a lead on the third boy: another student told the principal the two victims were talking about plans to beat a kid named up. We see Sneddon in the school cafeteria, doodling pictures of geometric plants and diamonds, and we see him look up as Lee and Olivia approach him, not super surprised. Girls notice Aaron being picked up by FBI agents, and then suddenly the bad boy a couple grades up who steals hubcaps doesn't seem so dangerous anymore.
Back at the Harvard, the kid -- Aaron Sneddon -- continues to doodle while Olivia fills Broyles in: "He said it was pretty dark and he didn't see much after the boys chased him into the tunnel." Broyles wonders why the kid didn't tell anyone, like his parents, and it turns out he has no father and his mother is out of the country a lot for work. He stays with a neighbor in their apartment complex. "His principal said that he's a quiet boy, that she doesn't know him to have many friends."