Herb Clutter: Herb Clutter, 48, is the father of the Clutter family and becomes a murder victim.

Bonnie Clutter: Bonnie Clutter, 45, is the mother of the Clutter family and becomes a murder victim.

Nancy Clutter:
Nancy Clutter, 16, is the third of the Clutters' daughters and becomes a murder victim.

Kenyon Clutter: Kenyon Clutter, 14, is the Clutters' only son and becomes a murder victim.

Perry Smith:
Perry Smith is one of the men who murders the Clutter family and is later hanged for the crime.

Dick Hickock: Dick Hickock is one of the men who murders the Clutter family and is later hanged for the crime. He is the mastermind behind the crime.

Alvin Dewey: Alvin Dewey is the Kansas Bureau of Investigation's lead investigator on the Clutter case.

Lowell Lee Andrews: Lowell Lee Andrews is a murderer on death row who killed his parents and his sister. Andrews is schizophrenic but cannot plead insanity in Kansas.

Barbara Johnson: Barbara Johnson is Perry Smith's sister, who is estranged from him and fears him.

Bobby Rupp: Bobby Rupp is Nancy Clutter's boyfriend who is quickly cleared of any wrongdoing at the start of the Clutter murder investigation.

“It’s important always to have with you someone of your own.” - Boonie Clutter.
Bonnie Clutter says this to Jolene, a girl who has just had a pie- baking lesson with Nancy but had to stay and wait for her mother to pick her up. Bonnie shows Jolene her collection of miniatures and gives one to Jolene to keep. Bonnie's ambivalence about her role in the family is reflected in the quote, which also mirrors how Perry Smith took boxes of his possessions and mementos with him everywhere.

The American Dream:
In Cold Blood is a reflection on the American Dream, tragically juxtaposing those who achieve it with those for whom it is out of reach. The Clutters realize the dream of financial success and family values. Upstanding, morally strong Herb Clutter is a well-to-do wheat farmer, president of the National Association of Wheat Growers, and an active and involved member of his community. The Clutters' farm is the epitome of the "family farm" of the era. Even 16-year-old Nancy Clutter is the "town darling."

The American Dream is unattainable for Dick Hickock and Perry Smith, who are impulsive, profane, rootless, and lacking in morals. Dick grew up with loving parents who, although "semi-poor," did their best for Dick and his younger brother. Right out of high school Dick marries his sweetheart; they have children quickly and Dick finds himself in debt trying to support his family. He turns to theft, for which he has a natural talent. Perry Smith's childhood is abysmal and tragic, as he suffers terrible abuse at the hands of family members and other caretakers. He never has a real chance in life and goes through it without getting anything he wants.

Crime and Immortality:
Both Perry Smith and Dick Hickock leave prison ready to commit another crime, with no sense of wrongdoing or evil. The overriding theme Dick Hickock embodies is crime and immorality. He manipulates and takes advantage of anyone—even his parents, who gave him a loving and stable childhood, and friends whom he cheats out of money—without guilt. He only does things that benefit him, lies easily to cover his tracks, and uses people to get what he wants, whether money, alcohol, or women. He masterminds the plan to rob and kill the Clutters, which includes manipulating Perry to carry out the actual murders.

Capote contrasts Dick with the gentler yet more violent Perry Smith, whose anger and antisocial tendencies run deep. He did not want to kill anyone, but once in the Clutter home he lost touch with reality. He believes Herb Clutter to be a nice, soft- spoken man even as he slits his throat. After the Clutter killings, Perry is bothered to some extent by what he'd done and keeps trying to understand it. He tells Dick there must be something wrong with them. But Dick replies he is normal, doesn't want to talk or think about it, and wants to move on with things. Capote repeatedly presents Perry as the more "moral" of the two murderers, and forces readers to reflect on the relationship between his upbringing, his mental illness, and his behavior.

Mental Illness:
Paranoid schizophrenia, attachment disorder, and depression affect the narrative. Both a victim and the perpetrators of the crime at the heart of In Cold Blood have experience with mental illness. Since the birth of her last two children, Bonnie Clutter has suffered serious depression, to the point where she rarely goes out with her family and needs to be hospitalized periodically for treatment. She takes to her bed most days, and she cannot take care of herself, her husband, or her children, whom she also worries no longer need her.

Dick Hickock's car crash leaves him with a deformed face and an urge to engage in darker criminal activity. Having been a passable student and good athlete, he'd also been in trouble as early as his teenage years. Only his parents blame his lack of guilt and nonexistent moral compass on his accident. His neighbors think he came straight from "the devil," and psychologists diagnose him with an attachment disorder, which contributed to his ability to manipulate, lie to, and cheat even his loving parents and his good friends.

Suspense:
Truman Capote wrote In Cold Blood as a nonfiction novel, a piece of "narrative reporting" rather than straight journalism, creating one of the first true-crime novels. The objective in any crime novel is to heighten suspense, so Capote uses literary and cinematic devices such as foreshadowing, flashbacks, and withholding information to keep readers on the edge of their seats. For example, in the first section of the novel, the action cuts from Dick Hickock and Perry Smith pulling into the driveway of the Clutter farm in the middle of the night to the next morning when Nancy's friends come to get her for church and discover her body.

Capote also heightens suspense by describing what each of the Clutters do on the last day of their lives, while suggesting those lives will end badly. Alternating the steps the Kansas Bureau of Investigation's (KBI's) investigators are taking with the movements of Dick and Perry, who travel from Mexico to ultimately Las Vegas, also builds suspense. Even during the murderers' stay on death row, readers remain in suspense about when the executions will take place because appeals are filed and the date of execution is continually delayed.

Fear:
By using the narrative technique of foreshadowing—suggesting something ominous to come—Capote creates the fear of the unknown. The residents of Holcomb experience fear from the moment news of the murders spreads through town. For the first time in the small, tight-knit village, people lock their doors and suspect each other of wrongdoing. Entire families sit up all night, unable to sleep. The longer the case drags on without an arrest, the more people begin to resent the KBI agents for not finding the killers.