katy's mother angela witnesses the murder but persuades her not to call the police. they then go through a pretence that tommy had been killed by an intruder, until forensic evidence leads to angela's arrest. after a few weeks, katy decides she cannot live with the guilt any longer and writes a note confessing the truth about her father's death before committing suicide by drinking water mixed with sugar (a deadly solution, because of her diabetes). martin later finds her lying unconscious on the sofa with the note beside her. she is later taken to hospital, but dies two weeks later.