Six years ago, Nicola Edgington attacked Kerry Clark and Sally Hodkin in south London, seriously injuring Kerry, a 22yr old woman and killing Sally, a 58yr old mother and grandmother. She was prosecuted for murder and attempted murder, convicted in March 2013 and sentenced to life in prison with a minimum recommendation she serves 37yrs. She appealed against this outcome, but it failed. Four hours before the attacks, the Metropolitan Police had contact with Nicola, having been called to a taxi rank in Greenwich and they assisted her to the Emergency Department at Woolwich Hospital where she was seen by a mental health nurse and admitted on a voluntary basis to a nearby mental health unit. She absconded from the unit thirty minutes or so later, and attacked the two victims shortly afterwards as they made their way to work. If you prefer not to read a pile of material, there is a simple, but useful audio / visual summary of this on the BBC news website.