Cornelius Gerhardus van Rooyen was born on April 11, 1938, in South Africa. He was commonly known by the nicknames "Gert" and "Bokkie." Not much is documented about his early childhood or family background. However, it is known that he had a troubled upbringing.

In 1954, at the age of 16, Van Rooyen was sent to a reform school. This followed an incident where he stole a car. He drove it from Cape Town to Pretoria to see his dying mother. After this event, he continued to have legal troubles. In 1960, he was convicted for stealing motor parts and clothing.
 

Van Rooyen eventually married and had six children. Their names were Anne Marie, Judith, Hannes, Flippie, Gerhard, and Adriaan. He ran a construction business with his brothers and earned a living this way for some time.

He went through a significant life change in 1983 when he divorced his wife, Aletta. By 1988, Van Rooyen began dating a woman named Francina Johanna Hermina Haarhoff, often called Joey. The couple appeared to lead a very different life together, going on holidays and seeking to foster children, even though their application was denied.

Cornelius Gerhardus van Rooyen, known as Gert van Rooyen, was connected to the abduction and murder of at least six young girls between 1988 and 1989. These girls were aged between 11 and 16. Van Rooyen worked with his partner, Francina Johanna Haarhoff, who is believed to have helped him lure their victims.

Some of the missing girls included 14-year-old Tracy-Lee Scott-Crossley, who vanished on August 1, 1988, near Johannesburg. Shortly after, on December 22, 1988, 12-year-old Fiona Harvey disappeared in Pietermaritzburg. In 1989, 12-year-old Joan Horn and 16-year-old Janet Delport also went missing, along with 11-year-old Odette Boucher and 12-year-old Anne-Mari Wapenaar.

In one incident on January 11, 1990, 16-year-old Joan Booysen was kidnapped by Haarhoff. She was taken to Van Rooyen's home, where she was drugged and assaulted. Fortunately, she managed to escape and alerted the police. This led to Van Rooyen being identified as a suspect. Fearing arrest, he killed Haarhoff and then took his own life on January 15, 1990.

Despite extensive investigations, the bodies of the missing girls were never found. Items belonging to some of the girls, such as class captain badges and letters, were later discovered in Van Rooyen's home, linking him to the disappearances. In the following years, police searched his property and even demolished his house to find evidence, but no solid leads emerged regarding the fate of the girls.
 

In 1996, a renewed investigation took place, but it did not yield any new information about the missing girls. Reports of possible bones found near the holiday locations the couple visited did not match any known victims. Public interest in the case remained high, leading to features on investigative television shows. The lasting mystery surrounds the whereabouts of the victims and the circumstances of their tragic disappearances.