He was dubbed The Phantom Arsonist after Dexter Morgan noticed a void in the scorched area surrounding the first two victims, with the name "Bobby" mysteriously written at crime scenes.
When he was twelve, Joe helped his best friend, Bobby Hamilton, set their school's gym on fire, in which Bobby was inadvertently killed. When the fire was over, Joe was caught by the police and sent to a juvenile facility for six years, while blaming Bobby for it. During his time at juvie, he would often fight with the other children.
Two years after his imprisonment, Joe set his roommate's bunk on fire. His privileges were suspended for two months and he was forced to live in an individual room with higher supervision.
Joe was sent to a psychiatric facility for six years.
He was released, a month before the fires started.
The first arson victim was thought to have died by self-incineration (a form of suicide). At the next crime scene, Dexter Morgan noticed that a void was present in the soot and believed that someone was responsible for the death.
Initially, Dexter suspected Investigator Phil Bosso to be the killer, but cleared him. He then tracked down Joe Jensen in a juvenile database, by using his fingerprint.
Dexter set up a kill room in Jensen's house and almost killed him, until he realized that both Joe and himself blamed their killing on a childhood trauma. He then cut Joe loose, knocked him out, and called the police. When Debra arrived at the scene, she realized that Dexter had left Joe to be arrested.
- Danny Yamiro
- Leo Santolongo
- George Lee
- Chris Thomas
- Rhodes Mason
- C. Patterson
- I. Patterson
- Three unnamed bus victims
- Fire Inspector Phil Bosso
- Dexter appears to have set up his kill room in Joe's basement. However, most houses in Florida do not have basements. This is because the water table is so high.