In the episode written by series creators/executive producers Cheryl Heuton and Nicolas Falacci, skeptical Federal Bureau of Investigation (FBI) agents track an undetected serial killer while their math consultant copes with his brother's recent injury.
Charlie's obsession with the serial killer worries David, Colby, and FBI Special Agents Liz Warner (Aya Sumika) and Nikki Betancourt (Sophina Brown), as they suspect that Charlie may be suffering from post-traumatic stress disorder (PTSD).
[2] McGill and Gene Evans (John Rubinstein), a retired accountant/amateur police consultant, identify several unsolved cases in Fresno and Bakersfield, California, which fit Charlie's timeline.
FBI technician Matt Li (Matthew Yang King) gives Charlie a copy of Dr. Kim Rossmo's methodology.
Using the information from Evans and Li, Charlie realizes that the killer has previously moved twice before arriving in Los Angeles.
At the FBI office, Don and the team figure out that the serial killer is eliminating those who either witnessed and investigated the unsolved murders.
At the house, Charlie, Don, and their father, Alan Eppes (Judd Hirsch) reminisce about the brothers' first case.
As the team surveys the identified targets, the killer strikes one house but escapes when the agents attempt to arrest him.
To narrow the focus of the investigation, Charlie and David compare the social security numbers of the residents in the hot zones with census records.
[10] When asked about the 100th episode in separate TV Guide interviews, actors Alimi Ballard[11] and Rob Morrow [12] alluded to the Easter eggs.
On April 21, 2009, the cast and crew celebrated both the episode and the end of the season at the Sunset Tower Hotel.
Calling the episode "a knotty murder mystery", Tim Holland of TVGuide.com included "Disturbed" in TVGuide.com's Hot List for May 1, 2009.
[14] Jeffrey Robinson of DVD Talk stated that McGill's presence in "Disturbed" made the episode interesting.