Arson Investigator Phil Bosso states the incident was like the previous one, a petroleum-based accelerant with the intent of self-incineration (a form of Suicide). According to Phil, the killer poured the fuel or gasoline over his head, burning from a "center mass" upward and downward.
Dexter investigates the incident further, after requesting to close the doors so that he and Phil were alone inside. He notices a "void" within the scorch marks, just like the car beforehand. He mentions a "phantom", suggesting whoever killed Leo stood in the doorway blocking him from escaping while also watching him burn alive (wearing a protective suit to avoid personal harm). Of interest at this scene, the name "Bobby" is etched into the elevator door...Dexter wonders if this was the killer's name or the last person on his mind.
According to Detective Joey Quinn's report, he was a grad student with high promise. It's currently unknown why the Phantom chose Leo as a victim.