The Doomsday Killer Investigation is a police investigation into a series of religious killings in anticipation of the end of the world. The case in itself is the ninth major case in the series. The previous major case before this one is the Barrel Girl Case. The next major case after this is the s is the Mike Anderson Investigation.


James Gellar - Initially suspected of being the Doomsday Killer based on Professor Gellar's belief in the end of the world and his suspicion in the theft of an antique sword belonging to John the Revelator. Continued to be a suspect in the case and considered Travis' partner. Dexter makes sure Homicide never knows he is innocent.

Travis Marshall - Was suspected because of his connection to Professor Gellar back when he was a university at the same university where Gellar taught. Later confirmed as the killer when his sister ended up dead in the Whore of Babylon Tableau.

Steve Dorsey - Suspected of helping Travis in his latest killings and later confirmed when his body is found at the boat where they were brewing up a chemical weapon dubbed "Wormwood."

Beth Dorsey - Revealed to have targeted Miamia Metro with Wormwood and kidnapping Batista. 

Unsuspected Killers

Dexter Morgan - Was the actual killer of Steve Dorsey even though his murder was pinned on Travis Marshall. Later killed Travis Marshall and made it look like he killed himself with Debra's help.

History of Killer

Travis had a long history of violence before he began killing people in religious manners. When he was a child he forced his parents car off the road and killed them. He recieved psychiatric help for this but the treatments never helped him curb his killer tendancies. Eventually he went to University of Tallahassee where he met Professor Gellar and identified with him on his end of the world theories. Eventually Travis stole a sword and brought it to Gellar so they could start the Tableaus but was rejected by him and Travis killed him. After that Travis started killing people and eventually recruited the Dorseys to help him with his plans.

Detectives on Case

Other operatives involved in the case.


Omar Rivera -

Nathan Roberts -

Erin Baer -

Lisa Marshall -

Trent Casey -

Holly Benson -

Steve Dorsey -

Beth Dorsey -

James Gellar -

An unnamed couple was killed for access to their home after Travis was on the run and had no place to hide from the cops.

An unnamed cop was killed in order to make way for Travis' last step in order to end the world.


Closure of Case

The case is officially closed because Travis Marshall's burned corpse is discovered by the police. He is believed to have committed suicide in frustration of the world not ending (Although in reality, Dexter killed him and staged his death as a suicide).

Fate of Killer(s)

Dexter Morgan captured and killed Travis Marshall in his usual means and in revenge for trying to kill Harrison. Later on, Dexter staged Marshall's death as a suicide and ultimately his burned corpse was discovered, thus, leading to the case being closed for good.