On 21 April 2001, 14-year-old Hannah Williams told her mother she was going window shopping in Dartford, Kent, but never returned home. For a long period, investigators presumed she had run away, a theory reinforced when a friend reported seeing her after the date she is believed to have actually died. This assumption is described as having hampered the search for her.
Williams's body was discovered on 15 March 2002 at a cement works in an industrial area of Northfleet, Kent, beside the Thames estuary. Investigators initially speculated the body might be that of Danielle Jones, a schoolgirl who had gone missing from East Tilbury, Essex, in June 2001, but Williams's clothing led to correct identification. The discovery occurred around the same time investigators were also looking into the disappearance, and later murder, of Milly Dowler from Surrey, who went missing on 21 March 2002.
Robert Lesarian Howard, born 20 April 1944 in Wolfhill, County Laois, Republic of Ireland, was arrested on 23 March 2002, eight days after Williams's body was found. Howard was a convicted sex offender with a long history of violent offences, including a conviction as a teenager for burglary, a conviction at 19 for attempted rape of a six-year-old girl in London, and later convictions for attempted rape and strangulation in London and for burglary and rape in Cork. He had also been a police suspect in the disappearances of several women and girls in Ireland, including Jo Jo Dullard and Annie McCarrick. In 1993 he was convicted of unlawful carnal knowledge of a 16-year-old girl in Castlederg, County Tyrone. Howard had known Hannah Williams since 1999.
At his trial at Maidstone Crown Court in October 2003, Howard was found guilty of raping and murdering Hannah Williams and was sentenced to life imprisonment; no minimum term was reported as recommended by the trial judge or subsequently issued by the High Court. The jury in this trial heard evidence about his grooming of both Williams and Arlene Arkinson, a 15-year-old who disappeared in Bundoran, County Donegal, in August 1994 after last being seen in a car Howard was driving. Howard was tried in 2005 for Arkinson's murder but was acquitted, in a trial where the jury was not informed of his prior offences or his conviction for Williams's murder. A 2021 inquest into Arkinson's disappearance found Howard responsible for her murder and ruled that police should have arrested him immediately given his known history. Howard died in prison on 2 October 2015, aged 71.
Williams's case has been the subject of media criticism, with commentators alleging "missing white woman syndrome" affected coverage. Williams lived with her single mother in a household described as dysfunctional, came from a lower social-class background, and had learning difficulties. Commentators have contrasted the comparatively limited coverage of her case with the more extensive coverage given to other missing or murdered girls of similar age around the same period, including Danielle Jones, Milly Dowler, Leanne Tiernan, and Holly Wells and Jessica Chapman, who came from middle-class backgrounds with more stable home lives.