Joanne Dennehy, who killed three men and attempted to murder two others in 2013, was diagnosed with psychopathic anti-social personality disorder a year before her spree. Doctors found she exhibited anger, aggression, impulsivity, and irresponsibility, with no remorse for harming others. After her arrest, she was also diagnosed with paraphilia sadomasochism, deriving sexual pleasure from pain and humiliation.
Dennehy, born in St Albans in 1982, grew up in Harpenden with a younger sister. Her father was a security guard, her mother a shop manager. Friends describe her childhood as comfortable and ordinary; she played netball and hockey at school and was considered bright. However, in her mid-teens, she began skipping lessons, taking drugs, and drinking. At 15, she ran away with an older man, John Treanor, and left home for good at 16.
She had two children with Treanor but was a poor mother, often leaving for days. The relationship was stormy, and she cheated with both men and women. She worked as a labourer on farms, sometimes paid in alcohol, and engaged in self-harm. Her family became estranged after she demanded payment for them to see their grandchildren.
Despite her history of mental health problems and criminal record, her murderous spree shocked friends and police. Over two weeks in spring 2013, she killed three men, possibly due to annoyance or boredom after casual sexual encounters. She then sought more victims, narrowly failing to kill two others before being caught.
