Cleo Louise Eller is the murder victim in Pilot. She is known for having an affair with her boss, Senator Alan Bethlehem. She was approximately 5'3, with a Caucasian-African American race, and delicate features.
She was born in the late 80's to early 90's, and the only child to Ted and Sharon Eller. She often wore a thin chain around her neck, which had her father's medal that he had won in the first Gulf War that he gave to her for luck. When she was about seven years old, she broke her wrist while riding her bike. About two weeks before her wrist would heal enough to get her cast removed, she rebroke her arm when she got back on her bike. She graduated from high school and went to college, where she played tennis and at one point got bursitis in her shoulder. After college, she worked as an intern for the senator, where she had an affair with her boss, Senator Alan Bethlehem, while dating Ken Thompson, another employee of Bethelehem, his aide.
Oliver Laurier was Cleo's stalker, who later began to stalk the woman who was involved in solving Cleo's murder, Temperance Brennan. He stalked Cleo, who was aware of his obsession with her, which led to her boyfriend getting a restraining order against him, however, Oliver claimed he was simply her close friend and that he loved her.
Before death, Cleo was nauseous and in depression, and toke Lorazepam, Chlordiazepoxide and Meclizine Hydrochloride, medications used to treat nausea. She was pregnant, and told her boyfriend, which led to her death. The fetus had only developed ear bones, and it is never clear who was the father of her child - the senator or her boyfriend - due to the fact that there was not enough DNA.
Cleo was reported missing after disappearing on April 6, 2003, at 9:00 PM, exiting the Cardio Deluxe Jam on K Street. She never made it to her car. Ken Thompson. her boyfriend, snuck up on Cleo and proceeded to stab her 5-8 times with a military issue K-Bar knife, and it wasn't until Ken stabbed her 3-4 times that she stopped fighting and died of her stab wounds.
Ken Thompson then got rid of Cleo's body. He used the knife to prevent anyone from getting fingerprints from her to identify her by using the knife to remove the finger pads from her fingers, damaging the distal phalanges, the tips of her finger bones. He also laid her body on a floor of cement with traces of diatomaceous earth (a filtering agent used for filtering water, for Ken kept tropical fish) while striking her head 4-5 times with a 20 pound hammer with a head of rolled steel. He removed her clothing and wrapped her in weighted PVC chicken wire to prevent her body from floating during decomposition. He then planted a little booklet that her stalker handed out to people in her hands to frame him, as well as using a military knife and hiding her body near a military cemetery to frame her own father. He then threw her body into a pond filled with microbes, black carp and koi, which sped up the decomposition rate of her body.
When Cleo's body was found by a landscaping workman, Brennan eventually finds that Ken is the one who killed Cleo. When she finds Ken destroying evidence at his residence, she breaks down the door by bashing in a pot into the glass tiles to open the locked door. She finds that he has covered up the cement floor with linoleum and swept the place, and currently spilling gasoline in the floor. When she questions why he's destroying evidence, he warns Brennan to get out while getting out a lighter to burn down the house by lighting the trail of gasoline. Brennan shoots Ken with her gun, and he immediately drops to the ground on impact with the bullet, and drops the lighter. When she questions the psychology in his motive, Laurier comes in. She orders him in a stressed tone to apply pressure to his wound. Booth explains how Ken is the one who killed Cleo, and he did it to save his job. Ken is then found guilty and is sentenced with life in prison with no parole.