Disappearance of Rhianna Barreau

Rhianna Ann Barreau, born in 1980, was a 12-year-old Australian girl who went missing in October 1992 from her home in Morphett Vale, South Australia. South Australia Police have described the case as one of the "largest files" involving major crime in modern times, though no suspect has ever been officially named. She was suspected to have been abducted and murdered, but her fate remains unconfirmed.

On the morning of Wednesday, 7 October 1992, Rhianna and her mother, Paula Barreau, had planned to meet for lunch at the nearby Colonnades Shopping Centre, close to Paula's workplace. Rhianna wanted to buy a card for her overseas pen pal, but a snap public transport bus strike affected her planned commute. After Paula left for work at 8:30am, Rhianna is thought to have stayed home until she was seen walking to the Southgate Square Shopping Centre at 10:30am, where she bought a Christmas card at 11:19am for her pen pal.

Between 12:05pm and 12:30pm, Rhianna was sighted crossing the grounds of Morphett Vale High School and Stanvac Primary School carrying a small bag, presumed to hold the Christmas card. At 12:30pm she was seen again walking along Highway Drive. It is believed she returned home afterward, since the bag was later found on the dining table, though the exact time of her arrival home is unclear. When Paula Barreau returned home at approximately 4:10pm and entered through the locked door, she found the television on and a vinyl record on the living room floor. The unopened bag containing the Christmas card remained on the dining table. Rhianna was not present, and she has not been located since.

Police declared the case a major crime two days after her disappearance. Retired South Australia Police detective Allen Arthur said a lack of community assistance would hinder the investigation, and noted it could become another unsolved case like the disappearance of the Beaumont children or the Adelaide Oval abduction. By 25 November 1992, police had received more than 1,600 calls related to the case. That same month, a man called police from a payphone reporting he had found keys on a footpath on Highway Drive, but when he returned to the location, the keys were gone; the caller also said he had seen a young girl matching Rhianna's description near a white Torana on the day she disappeared.

Police also received a report from a witness who saw a white LH Torana sedan, with a black spoiler at either the front or rear, parked at the Stanvac Kindergarten carpark on the day Rhianna went missing. The vehicle reportedly had Victorian numberplates, though this detail was never confirmed and the car was never located. This possible interstate connection led to speculation linking Rhianna's disappearance to an unidentified predator known as "Mr Cruel," who was known to target young girls during school holidays. This link has never been confirmed.