On 4 November 2005, Edgington stabbed her 60-year-old mother, Marion, nine times in Forest Row, East Sussex[6] for which she was convicted of manslaughter due to diminished responsibility (based on diagnoses of schizophrenia and emotionally unstable personality traits)[3] at Lewes Crown Court on 23 October 2006.
[7] She was detained indefinitely under the Mental Health Act 1983 and, following treatment and psychiatric evaluation, was released conditionally in September 2009,[8] moving into a Greenwich flat.
[3] On the morning of 10 October 2011, Edgington pleaded numerous times with police and local mental health services to physically detain her under their legal powers as she felt she was having another psychotic breakdown, saying she had killed someone before and that the more scared she became the more dangerous she could be.
[3] Later in the morning of 10 October 2011, while waiting for staff to change shift and admit her, Edgington left the hospital through a door that should have been locked, took two buses, and stabbed two strangers in the street in separate attacks in Bexleyheath.
Edgington subsequently stole a knife from a butcher's shop then stabbed and nearly decapitated[13] 58-year-old Sally Hodkin, who died of her injuries within minutes.
[9] Barker wrote that despite Edgington's firm long-standing diagnosis of schizophrenia and probable psychosis around the time of the attacks, he believed the over-riding factor was borderline personality disorder (known as "emotionally unstable personality disorder, borderline type" in the UK)[15] with rational ability.
Despite Edgington having sought multiple times to have herself detained by the police or medical services prior to her actions, Barker stated that the killing was premeditated in a way that showed a "consistent and calculated course of criminal conduct".