On Monday June 3rd 1991 bank clerk Alison O' Shaughnessey was found stabbed 54 times at her Battersea, London flat. She had most likely opened the door to her killer and hit from behind unawares. After Police found that a local girl, 19-year-old Michelle Taylor, had been having an affair with the victim's husband, a case was made against her and her sister Lisa, alleging that the latter had acted as lookout whilst Michelle perpetrated the killing. The girls were convicted of the crime in July 1992 but freed on appeal in 1993 on the grounds of prejudicial press coverage.
There's a video of the story here:
https://youtu.be/nYcNw_y2q7I..and a more sympathetic appraisal here, however forced the girls' smiles appear as they emerge from court at the Old Bailey as free young women once again.
http://www.nickdavies.net/1993/06/01/a-murder-and-a-miscarriage/