A forensic psychologist has provided a rare and disturbing glimpse into the mind of Joanne Dennehy, one of Britain's most notorious female serial killers, whose bloody rampage in Peterborough left three men dead.
The Chilling Spree and a 'Moreish' Addiction to Killing
In March 2013, over a ten-day period, Dennehy embarked on a killing spree that shocked the nation. Her victims were Lukasz Slaboszewski, 31, her romantic partner; John Chapman, 56, her flatmate; and Kevin Lee, 48, her landlord with whom she had begun a sexual relationship. She callously disposed of their bodies in a ditch.
Speaking to an accomplice about her desire to murder, Dennehy stated, "I want my fun. I need you to get my fun." In a later psychiatric assessment, she chillingly described the act of killing as "moreish and fun." She even joked after a murder, "Oops, I've done it again," showcasing a complete lack of empathy. Prior to her capture, she also carried out random, non-fatal attacks on two other men.
A Psychologist's Analysis: Rare Sadism and Zero Remorse
Psychologist Phil Macleod, analysing the case, described it as "deeply unsettling." He highlighted the extreme rarity of such sadistic violence in women. "What makes it so rare - and frankly so shocking - is that this level of extreme violence and sadism is almost unheard of in women," Macleod explained.
He pointed to Dennehy's complete absence of remorse and her fixation on control and humiliating her victims. She reportedly used sexual behaviour to lure them, killing to test her own coldness and finding the experience addictive. "She seems to have used sexual behaviour to lure her victims," Macleod noted.
Dennehy's psychological profile included diagnoses of a personality disorder and sexual sadism. The personality disorder created ingrained patterns that made feeling empathy or guilt nearly impossible. The sexual sadism diagnosis meant she derived pleasure from the suffering of others—a pattern Macleod stressed is extremely rare in female offenders.
From Affluent Childhood to Lifelong Danger
Despite being raised in an affluent part of Hertfordshire, Dennehy's life spiralled into alcohol, drugs, and petty crime by her mid-teens. She left home at 15 to live with an older man, John Treanor, with whom she had two children. The relationship was violent, and Dennehy began carrying a dagger and speaking openly about wanting to kill.
After Treanor left, taking the children and leaving her homeless, Dennehy's behaviour escalated. In 2012, she was arrested for theft and, while in prison, was diagnosed with anti-social behaviour disorder. Upon release, she met Kevin Lee in Peterborough, beginning a relationship and working as his rent 'enforcer'.
Her final crimes led to a life sentence in 2014, with the judge ruling she was so dangerous she must remain imprisoned indefinitely. Even in custody, she allegedly menaced fellow serial killer Rose West upon arrival at HMP Bronzefield to establish herself as the prison's "top dog." A prison source stated other inmates were scared of her due to her crime and attitude.
Macleod concluded that Dennehy's case is a tragic reminder of how untreated, extreme psychological disorders can have devastating consequences. "This is not just criminal behaviour... it's a profoundly abnormal mental state that challenges what we think we know about the mind, gender, and violence," he said. The courts' assessment that she can never be released stands as a stark testament to her enduring threat.
