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Joanna Dennehy – Female Killer behind the Peterborough Ditch Murders

Female serial killers occupy a unique place in the true crime spectrum. They differ to their male counterparts somewhat significantly in terms of their victimology, method of murder and their motivations. In most cases, female murderers do not kill for lust or sexual gratification, unlike the majority of males. The prime motivation for a female serial killer is material gain.

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What this means is that the act of killing is not the female killer’s primary desire, it is the end result they crave. They want a person gone so that their lives are enhanced; murder is a means to an end. However, as with everything in life, there are always exceptions. Notable female lust killers have appeared sporadically over the years, however, few of them match the violence, manipulation and pure sociopathy shown by Joanna Dennehy.

Joanna Dennehy

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In 2013, 31-year-old Joanna Dennehy stabbed three men to death and wounded two more within mere days of each other in Peterborough, England. At the time, the case was a media sensation, and to this day remains topic of macabre interest amongst the British public. The now-infamous picture of Dennehy brandishing a knife with a smug grin on her face is etched in the collective conscious of all those familiar with her crimes, and she will no doubt remain a figure of detest for the rest of her life.

But what made Joanna Dennehy – a girl from a background of privilege and opportunity – become a murderous monster?


Joanna Dennehy was born in 1982 in small town in Hertfordshire, England. Her early years and home life appeared to be idyllic and without issue; her parents worked hard and cared dearly for Joanna and her sister, Maria. Their mother owned a local shop and their father was a security guard – both of whom earned decent money and were able to raise their children comfortably in their four-bedroom detached house.

Joanna was academically advanced during her primary school years, showing signs of great potential in certain subjects. She was particularly talented in music, with her parents affording her extra-curricular tuition and piano lessons. Her parents make no claims of any troublesome issues at school, home or amongst friends, and there are no reports to suggest otherwise.

When Dennehy hit her teenage years, this was when she began to show signs of distress. At the age of 13, Dennehy ran away from home with a man who was older than her, although sources vary on the man’s age. She soon returned, but would regularly run away again for days at a time. She began to steal from her parents, shops and individuals. She began hanging around with undesirable crowds, the majority of which were older males.

It was at the age of fifteen that Dennehy’s life became truly entangled in a web she would never escape. She got together with a man named John Treanor, who very quickly got Dennehy pregnant – despite her being only fifteen and Treanor being twenty.

Dennehy and Treanor ran away together, eventually ending up several miles from her parents’ home in Hertfordshire. As the years past, both Dennehy and Treanor’s life spiralled into an inescapable pit. The pair were both alcoholics and drug addicts. Dennehy became estranged from her parents and claimed that if they would have to pay to see their grandchildren, of which Dennehy gave them two by the time she was 21. She became increasingly aggressive towards everyone she came into contact with, including her partner.

Their relationship became rocky as a result of Denney’s increasing capacity for violence. She would get drunk and beat him, sometimes in front of their children. Dennehy would run away for days on end, neglecting her children, and usually sleeping with other men during her absence. She began to self-harm; something which would be an indicator of her future behaviour. She even threatened Treanor with a knife, which made it clear to him that he needed to leave Dennehy for the sake of his life.

Joanna Dennehy
Joanna Dennehy


Treanor left Dennehy in 2009 and took their children with him. Dennehy moved from place to place, eventually ending up in a small flat in Peterborough. She became acquainted with a man named Kevin Lee who owned a letting agency, and who then provided Dennehy with regular work. She acted as a kind-of bounty hunter for Lee. She would evict tenants who hadn’t paid their rent from Lee’s properties, and it was a role Dennehy clearly enjoyed.

Dennehy was able to instil fear, dread and worry into people and received payment for it. To her, it was her perfect job. She clearly enjoyed the power which she took from it and soon became invaluable to Lee.

Dennehy and Lee soon began a romantic relationship, with Lee even allowing Dennehy to live in one of the properties he owned. It seemed that Dennehy had clawed back some structure to her life, although this would quickly dissipate.  

On 19th March 2013, Dennehy invited a man named Lukasz Slaboszewski into her home. She had met him around Peterborough one afternoon, and manipulated him into thinking she was interested in a romantic relationship with him. She wasn’t, and was simply scoping out her first murder victim.

Slaboszewski arrived at her apartment, and the two of them drank for several hours. Eventually, Dennehy put a blindfold over Slaboszewski’s eyes under the guise of playing a sex game. She then picked up a knife and stabbed him through the heart.

Attempted murder and murder is nothing. It’s like going down for a Sunday roast, easy.’ – Joanna Dennehy

Reports state that Dennehy showed no signs of concern to the fact she had just committed a homicide. She showed calm detachment from the fact, although she later claimed severe pleasure from the act of killing him. Dennehy realised, however, that she wasn’t capable of moving Slaboszewski’s corpse by herself, so she called a friend of hers named Gary Stretch.

Stretch was a known criminal in the Peterborough area and had become acquainted with Dennehy through the evicting jobs she had done for Lee. It seems that Stretch was another man who had become romantically interested in Dennehy, although she showed no signs of reciprocation towards him. It is likely due to this unfounded admiration that Stretch agreed to help Dennehy dispose of Slaboszewski’s body as opposed to address the seriousness of the situation and call the police.

Gary Stretch
Gary Stretch

Stretch, Dennehy and a friend of Stretch’s named Leslie Layton all showed up to help Dennehy rid her flat of Slaboszewski’s torso. They put his body in a wheelie bin and covered it with rubbish, soil and bricks. Around a week later, they took the body to a secluded area and disposed of it.

Dennehy would commit her second murder ten days later. 56-year-old John Chapman was a tenant in the same apartment complex as Dennehy, and Dennehy had manipulated Chapman in the same way she had Slaboszewski. She made subtle hints at sexual activity, to which Chapman invited her into his home. After several drinks, Chapman passed out. Dennehy then picked up the same knife she had used for her previous murder and stabbed Chapman six times in his neck and chest.

Dennehy called her now-trusted companions, Stretch and Layton to help dispose of Chapman’s body. They did so in an identical manner to Slaboszewski, hiding him in a wheelie bin and then discarding him in a ditch a week later.

The very same day, Dennehy committed her third and final murder – none other than her lover Kevin Lee. Lee was well-aware of Dennehy’s capacity for violent and unpredictable behaviour, but it seemed to be an attraction for him. Lee showed up at Chapman’s flat that same evening and, in very much the same way as Slaboszewski, blindfolded Lee under the ruse of sexual promiscuity.

When suitably deprived of his senses, Dennehy stabbed Lee through the heart repeatedly. His body was picked up by Stretch and Layton and disposed of in a ditch.

It seemed that Joanna Dennehy was now a spree-killer. Unlike a serial killer, a spree killer does not require a “cooling off period” in order to meditate on their crimes. A serial killer’s bloodlust is usually satisfied after one murder, rendering the urge to kill dormant until the compulsion re-appears. During this period, they detach from their actions and resume a normal life.

Dennehy, by contrast, was constantly in this hyper-state of needing to kill. This makes her perhaps the most dangerous of all types of cognitive abnormality. It means that Dennehy did not care who she killed and there was no reason or method to her madness. Everything about her attacks would be unpredictable: victim, method, location, severity.  

As was certain, Dennehy would attack twice more several days later, although her victims would fortunately survive. Her crimes had become known to authorities, and so she and Gary Stretch went on the run. As they were driving around Hereford, Dennehy exited their car and stabbed a man named Robin Bereza in the shoulder in a blitz attack. As Bereza was disoriented, Dennehy ran back to their car and drove away.

Around ten minutes later, Dennehy did the same again. She jumped out of the car and blitz attacked 57-year-old John Rogers, stabbing him a total of 40 times.

Murder Victims

Lukasz Slaboszewski
Kevin Lee
John Chapman

19 March 2013
29 March 2013
29 March 2013


As both these victims survived, police were able to learn that the perpetrator had a distinctive star tattoo on her face. It soon became clear it was Joanna Dennehy who was responsible for the attacks.

Due to their haphazard practices, Dennehy and Stretch were found and arrested within several days. It was a very open and shut case for authorities. Physical and circumstantial evidence existed to place Dennehy at the crime scenes, not to mention that she confessed to all murders without hesitation.

Dennehy received a whole life tariff, one of three women prisoners to ever do so in England and one of two who are still alive (Rose West, Myra Hindley). Dennehy showed no sign of remorse during any of the court proceedings, reportedly grinning, smirking and even singing during her trial. Stretch and Layton received jail time for perverting the course of justice.

Joanna Dennehy after her arrest.
Joanna Dennehy after her arrest.

Reason behind the Murders

It seems that Dennehy’s reasons for committing these heinous acts were a combination of factors which, together, made her an inhuman, remorseless killing machine. Firstly, debates regarding Dennehy’s classification as a psychopath or sociopath are widely discussed, however it is likely impossible to determine due to the other psychological disorders she possesses. Dennehy was confirmed to suffer anti-social personality disorders, obsessive compulsive behaviour, emotional instability disorders and paraphilia sadomasochism (excitement and sexual arousal from giving and receiving pain).

These multiple psychological abnormalities make it extremely difficult to determine why Dennehy’s acted the way she did, and indeed, which one may have been her overriding force. After her incarceration, she told a prison psychologist that she “just wanted to feel” what it was like to murder.

Author’s Opinion

The power which Dennehy was able to command over the men in her life is something rarely (if ever – I personally cannot name any other circumstance) seen in the annals of true crime. It is always the dominant partner who is the one controlling matters, and this is always the male in my experience (Ian Brady, Fred West, Paul Bernardo, Charles Starkweather). Gary Stretch did also not seem a submissive man by any means. He was well-built, naturally dominant and a career criminal. Yet, Dennehy was still able to manipulate him into being her puppet.

Finally, Denney’s method of murder appears inconsistent with everything else we know about her. By all accounts, her murders are lust kills. Dennehy suffers from a condition in which pain sexually arouses her, yet there was no prolonging of her victims’ agony in order to sexually gratify her sadomasochistic urges. It seems that, to Dennehy, the desire to kill was more important than the act of killing.

The case of Joanna Dennehy is as unique as it is fascinating. Whatever her reasons for killing may be, her crimes will live on in the collective conscious for the foreseeable future. We will likely hear much more of her as the years go by, perhaps even uncovering further information about her life, crimes and motivations in order to solve this complex, seemingly un-answerable puzzle. While it is a small victory that she will remain incarcerated for the rest of her life, a much bigger victory is that we can use this case for means of advancement. With unique cases comes new knowledge, and it is with this knowledge that we advance our understanding of the criminal mind.