When we picture a person responsible for some heinous crime - be it real or fictional - we probably imagine someone ice-cold and sinister: a loner, an aggressor, somebody who exudes a palpable sort of evil from every aspect of their demeanor. Think Christian Bale in American Psycho, for instance, or Ian Brady and Myra Hindley (the Moors Murderers).
It just seems incomprehensible that someone who looks so "normal" - who looks nice, even - could possibly be a threat to their fellow friends and neighbours.
So, when Velma Barfield (née Margie Velma Bullard), a seemingly sweet woman in her fifties, confessed to multiple murders, the world was stunned.
Barfield was born in a rural part of South Carolina in 1932, but spent most of her childhood in the neighbouring North Carolina. By all accounts, her youth was not a particularly happy time, and her father was reportedly very abusive. In order to escape that lifestyle, she married young - being just 17 at the time - and went to live with her husband, Thomas Burke.
Their marriage was a happy one at first. They had two children together, and appeared to be living a fairly contented lifestyle. However, later on in their relationship, Barfield had a hysterectomy, and subsequently developed an addiction to painkillers after the procedure left her with chronic back issues. This apparently caused a change in her personality which, in turn, caused her husband to turn to drinking.
After that, the couple would have vicious arguments, and the tension between them only ended when their relationship did. And how did that happen? Well, one night in 1969, when Burke was passed out drunk on the couch, Barfield took their children out. By the time they returned, their home was burnt to the ground.
From that point onward, Barfield's life was littered with a suspicious amount of death.
In 1970 - mere months after the woman's first husband had perished in a fire - Barfield remarried, this time to a widower named Jennings Barfield. Once again, however, their relationship quickly deteriorated after he confronted her about her misuse of prescription drugs.
Less than a year after they were married, the widower died after contracting a mysterious illness and suffering a heart attack.
From the outside, it appeared as if Velma Barfield simply had bad luck when it came to choosing husbands - but she knew otherwise. Even so, other people didn't begin to suspect there had been any foul play until years later, by which point the woman had offed at least six people.
Her next victim - shockingly - was her own mother.
In 1974, Lillian Bullard (Barfield's mother) developed an aggressive illness, the symptoms of which were nausea, diarrhea, and vomiting. She actually managed to recover from it once, but it struck again around Christmas time of the same year - and that time, she wasn't as lucky.
After that, in 1977, three more people died after coming into contact with Barfield. Montgomery and Dollie Edwards, an elderly couple that Barfield worked for, passed away within weeks of one another, with Dollie suffering from exactly the same symptoms as her caretaker's second husband.
With both her clients dead, Barfield had to take another caretaking job; this time for 76-year-old Record Lee, who had recently broken her leg. Lee actually survived Barfield's murder spree but her husband, John Henry, succumbed to a severe gastrointestinal illness that caused - you guessed it - severe nausea, diarrhea, and vomiting.
In 1978, Barfield ended the life of her final victim. His name was Rowland Stuart Taylor and he was a relative of one of Barfield's previous targets, Dollie Edwards. The twice-widowed woman was in a relationship with Taylor, but was also using him by forging checks in his name. After fearing he might have found out about her illegal activity on her account, Barfield sorted the matter in the only way she knew how to by this point: murder.
Taylor died the day after attending a church service with Barfield and, once again, everyone thought she was simply unlucky. This time around, however, a woman claiming to be Barfield's sister called police and informed them that she believed the widow had poisoned her boyfriend. In fact, she said, Barfield had killed several others before using the same method.
Sure enough, after investigation, autopsy results found arsenic in Taylor's system, and tests performed on the bodies of John Henry, Lillian Bullard, Dollie Edwards, and Jennings Barfield all showed traces of the poison, too. Barfield would eventually confess to four of these murders, plus the murder of Montgomery Edwards, but always denied killing her second husband.
She was never tied to her first husband's death, either, but it's always been suspected that she might have had a hand in it.
In the end, Barfield was only convicted of the first-degree murder of Stuart Taylor - but that was enough to get her the death penalty. She spent six years on death row, during which time she became a born-again Christian and earned herself the nickname, the "Death Row Granny".
She was the first woman ever to be put to death by lethal injection in the USA - much to the disagreement of anti-death penalty campaigners and fellow Christians who had asked for Barfield's sentence to be commuted to life imprisonment.
Before she died, Barfield said: "I’m sorry for any hurt I’ve caused anybody. There isn’t a day goes by that I don’t think about this and wish that it were possible for me myself to take that hurt."
To this day, she remains one of the most prolific female serial killers of all time.