On March 30, 2013, a member of the public found the body of Kevin Lee in a ditch near Newborough, outside Peterborough. He was forty-eight, a property developer and landlord with a wife and family, which is why he had been reported missing at all. He had also been Joanna Dennehy's lover. She had stabbed him to death the day before and dressed his body in a black sequined dress before it was dumped. Once police began looking into his affairs, she was the person they wanted to find. By then she had already killed two other men, and within days she would stab two more.
The first was Lukasz Slaboszewski, a thirty-one-year-old Polish man who had come to know her through a shared taste for drink and drugs. She killed him at some point between March 19 and March 29, stabbing him in the heart, and put his remains in a bin, where she brought a fourteen-year-old girl she had befriended to look at them. John Chapman, fifty-six, shared a house with her; she stabbed him in his sleep on March 29, the same day she killed Lee. The bodies of Slaboszewski and Chapman were found on April 3 in a ditch near Thorney, and at first nobody connected them with Lee. Pathologists later found that the same knife had been used on every one of her five victims.
Dennehy was thirty. Born in St Albans, Hertfordshire, in August 1982 and raised in nearby Harpenden, she was the mother of two young daughters she had largely left behind, and at the time of the killings she was under the supervision of the probation service for assault and for owning a dangerous dog. A later review found that the staff handling her case had been inexperienced.
After the killings, her friend Gary Stretch, a man more than seven feet tall who had once been known as Gary Richards, drove her west to Hereford. A third man, Mark Lloyd, was in the car against his will and was later cleared of any part in what followed. Lloyd said she boasted of the killings, wanted to kill nine men in all and spoke of herself and Stretch as Bonnie and Clyde, and that she would not kill a woman, least of all one with children. "I want my fun," she told Stretch. "I need you to get my fun." The pair recorded their days on a stolen camera; in one picture she holds a large dagger with her tongue out toward the blade.
On April 2, with Stretch picking the targets, she jumped from the car and stabbed Robin Bereza, sixty-four, in the shoulder, leaving him on the ground in his own blood. Nine minutes later she attacked John Rogers, fifty-seven, and stabbed him more than thirty times. Both men had been out walking their dogs, and she took the second man's dog with her. Both survived and were able to describe her. She was arrested in Hereford, calm to the point of coldness, and was said to have sung "Singin' in the Rain" as she was led to the cells. Interviewed on April 12, she answered questions about the stabbings with "No comment." On May 8 she was charged with the murder of Kevin Lee and the attempted murders of Bereza and Rogers; the Slaboszewski and Chapman charges followed.
The prosecution's worry was that she would plead insanity. Instead, on November 18, 2013, at the Old Bailey, she pleaded guilty to three murders, two attempted murders and three counts of preventing the lawful and decent burial of a body, taking her own lawyers by surprise. When they asked for time to talk to her, she told the judge, "I've pleaded guilty, and that's that." Her sister Maria said she had done it to stay in control: "She likes people to know she's the boss." Psychiatrists diagnosed psychopathic, antisocial and borderline personality disorders and a sadomasochistic paraphilia. She told one of them that she had killed to see whether she was as cold as she thought she was, and that after the first killing it became "more-ish." A witness at the later trial said she had boasted of killing eight people; she was never accused of more than three.
On February 28, 2014, Mr. Justice Spencer called her "a cruel, calculating, selfish and manipulative serial killer." She had written to him to say she was not sorry for the murders, and he rejected her claim to feel remorse for the Hereford attacks. Because each killing had been premeditated, he ordered that she never be released. She was thirty-one, and only the third woman in Britain to receive a whole-life order, after Myra Hindley and Rosemary West. Stretch, tried separately, was convicted of the two attempted murders and three counts of preventing lawful burial and given life with a minimum of nineteen years. Leslie Layton, thirty-six, convicted of perverting the course of justice and other charges, received fourteen years, and Robert Moore, fifty-five, who admitted assisting an offender, received three.
Her time in custody has kept her in the news. While she was on remand at HMP Bronzefield in Surrey, staff found a plan in her diary to kill or seriously injure a prison officer, cut off one of the officer's fingers and use it to beat the prison's biometric locks. She was held in segregation from September 2013 to September 2015, and the High Court rejected her claim that the isolation, which she said left her tearful and self-harming, had breached her human rights; Mr. Justice Singh found it lawful, necessary and proportionate. In 2018 she asked permission to marry a cellmate, and the same year the two women attempted suicide together. That year her elder daughter visited her and afterward cut off all contact, saying her mother felt no remorse. In 2019 Dennehy was moved to HMP Low Newton in County Durham, where she was reported to have threatened Rosemary West, who was moved elsewhere; the government denied the report.