The night of August 7, 1984, someone broke into the home where Margaret Tapp (35) lived with her two kids, Justin (14) and Seana (9). Margaret and Seana were strangled and left dead on their beds, and the little girl was also sexually assaulted. Justin wasn’t home that night, but the tragedy would eventually take a toll on him as well.

The bodies of the two Tapp women were found the next day by a man who had a date with Margaret. He was investigated as a suspect, and eventually cleared. The investigation turned up several clues. A witness stated that they’d heard a muffled scream around 11 pm, something that stood out in the quiet Ferntree Gully, Victoria, neighborhood. There was a pizza still in the oven and Dunlop Volley shoeprints left in Margaret’s bedroom and bathroom that police decided belong to the killer. Semen stains were also found in Seana’s nightgown, along with unknown hairs.

The list of suspects was incredibly long, and most of them were connected to Margaret, who was a lively, social nurse who dated freely. According to her friends, she’d had several affairs with doctors she worked with. One of them in particular was a married doctor who owned the house Margaret lived in and had died before Margaret’s murder. The doctor’s widow was considered a suspect after accusing that Margaret had harassed them several times. There was also her ex husband, Don Tapp, who was cleared after proving his alibi; a retired policeman and friend of the family who had made advances on Margaret but was rejected; a teenager who cut her lawn regularly and even the boyfriend of Margaret’s sister, who’d gone by her house on the day after the murders but left when no one answered the door.

Most of this people were cleared by DNA testing. Then, in 2008, police announced that they’d found a match and charged a man called Russell John Gesah, who was already in prison. But two weeks later, authorities admitted they’d made a mistake: the sample had been contaminated and the charges were dropped. 

In June 2014, as the 30th anniversary of the crime approached, Justin Tapp was found dead in his England home, of an apparent overdose of alcohol and drugs. The murder of his mother and sister remains unsolved.