Jeff is married to a woman named Shirley, they have a son together and is extremely paranoid that she is cheating on him. Jeff reveals in the final mission that his mother left his father, which probably traumatized him into his current state. Despite having obvious mental problems and wearing shabby clothes, he is an extremely wealthy businessman with a black credit card. Shirley became distressed by his paranoid behavior, such as sending her underwear to a laboratory and demanding she get a tracking device in her head. She then turned to another one of Jeff's wealthy friends for emotional support, and although he was secretly interested in having an affair with her, Shirley was only going to him for a platonic friendship and was very näive to his obvious attraction cues.
Jeff discovers that his wife has been interacting with his friend, and follows them to his friend's apartment near Lancaster, when he randomly encounters Niko Bellic. He pays Niko to take reconnaissance photos of his wife and friend (driving in Shirley's Feltzer to the Superstar Café). Niko successfully sends him a photo by text message, and seeing they were platonic friends, consoled Jeff that it wasn't necessarily proof of her cheating on him.
Ten game days later, Jeff calls Niko to request his services and meet him in an underground car park. Despite Niko's advice, Jeff violently stabbed his wife fifty times with a kitchen knife and hid her body in a Blista Compact, now asking Niko to dump the car in the Humboldt River. Niko successfully does so, and is rewarded by Jeff.
Third encounter & death
- "Goddamn you! You're just like all the rest!"
- ―Jeff, before his death.
Later in the game, Niko encounters Jeff again near Drusilla's in Little Italy. He remarried in a remarkably short amount of time, and believed his new wife was cheating on him as well. He followed her to the restaurant in the same manner as he did with Shirley, where she was having a drink with her ex. Jeff then requested that Niko kill her, which a disgusted Niko refused, Jeff then decided to deal with it (kill his new wife) himself, and ran out into the street, where he was accidentally hit and killed by a Turismo. The driver - a stereotypically posh Englishman, calls 911, but quickly regrets his decision, and drives away from the accident as soon as the police put his call on hold.
- Shirley - Murdered on suspicions of cheating on him. (alternatively, she can be killed by Niko Bellic.)
- GTA IV
- Three Random characters (If Shirley Harlingford is killed in the first encounter, the other two encounters will not appear/be killed in the last encounter)
Jeff's Random Encounters
- The first cutscene when meeting Jeff is loosely based on a scene in the film Taxi Driver, in which a man plans on killing his adulterous wife and spies on her and her lover outside the lover's apartment.
- Jeff, along with Brian are the only random characters to appear in three encounters.
- Jeff will appear as a contact in the player's phone until his death.
- Jeff suffers from Angina, a severe heart condition, possibly due to his incredibly short fuse and violent temper leaving him frequently over-stressed and anxious.
- Jeff's "Black card" is a parody of the American Express Centurian and Visa Black Card, both black-colored credit cards given to multi-millionaires.
- It is possible to steal the Turismo Jeff gets hit with, by entering it before the driver gets back into his car after making the phone call. It will not hinder the completion of the random character mission.
- Jeff's missions do not count towards 100% Completion as you can kill his wife (or his wife's friend) during his first random encounter. This will block the two other random encounters, so Jeff will not die.
- The only downside to this, however, is Jeff's contact will remain in Niko's phone permanently if the player chooses to kill his wife and/or friend, although Niko will be unable to call or receive calls from him.
- The underground car park Niko meets Jeff in during his second encounter is the same location that The Ballad of Gay Tony mission Going Deep takes place in.
- During the second encounter, the GPS will tell the player to turn right and exit the underground car park. It is a better idea to ignore this and turn left, as there is a police car waiting at the right exit.
- At the start of the first encounter, any cars parked in the vicinity will disappear on most, if not all, occasions, and a Stallion may be provided for Niko.
- When precisely used, Niko can shoot the driver of the Turismo with an MP5 or Micro Uzi, making him stop. The mission won't continue and Jeff will stand in one place. To pass the mission, kill the British man. When you do that, Jeff will walk away like nothing happened.
- Killing his wife's friend will result in Niko saying he killed him, and no thanks was required, but Jeff would say that he might have been her friend or her "pilates instructor".
- In his first encounter, Jeff shows Niko his card to prove that he is rich. Due to the camera angle, the card is never seen in-game, but it can be found in the game files. As his last name is never stated in game nor in the credits, this is the only source of it.