hanging with the wrong crowd

Joanna Dennehy was born in 1982 and grew up near St. Albans, Hertfordshire living with her mother, Kathleen, father, Kevin, and sister, Maria. Her upbringing was, by all accounts, a stable and loving one, and she did well at school throughout her junior years.
As she entered her teenage years however, Joanna began to experiment with drink and drugs and to spend more and more time with petty criminals.
At the age of 15 she left home and entered a relationship with the then twenty-year-old John Treanor whom she would subsequently have two children with.As their babies grew, Treanor and others around the family noticed Dennehy's increasing narcissism – she would put her own wants and desires above those of anyone else, including the children.
By this time Joanna was an alcoholic and drug addict and she and Treanor would often argue and fight. Joanna was self-harming – cutting her stomach with knives and razor blades – and had developed a hatred of her mother whom she would rant about. 

She was a petty criminal and served time in a juvenile detention facility for burglary.  She was manipulative and showed no remorse for her actions, nor any empathy for others. Sick of the violence and abuse, Treanor took the children and relocated, leaving Dennehy alone and homeless. In 2012 Joanna Dennehy was arrested and convicted of theft. She underwent psychological testing while in prison.
She was diagnosed with anti-social personality disorder. Underlying psychopathic traits were noted; rage, impulsivity, violence and anger. She was subsequently prescribed medication to regulate her moods.In 2013 Joanna met 48-year-old Kevin Lee in the town of Peterborough. Lee rented out cheap rooms to people who were vulnerable.
Lee began paying rent for Dennehy and the pair entered a sexual relationship. Joanna acted as Lee's paid “enforcer”, threatening and intimidating people into paying outstanding rent and other debts. With her rent paid, a porter of sorts, and a paying job, Joanna Dennehy felt her life was more stable than it had been for a long time. Convinced that she was in control, she stopped taking her anti-psychotic medication altogether.