Wilken was born in 1966 in Port Elizabeth, in the Eastern Cape, was given up as an infant and raised in a series of foster placements and children's homes in which he was severely abused. He worked as a security guard and lived on the edge of the city.
Between 1990 and 1997 he killed at least seven people and probably ten. There were two distinct victim groups, which is why the case is discussed in the literature on offender profiling: adult women he picked up as prostitutes, whom he strangled, and young boys, whom he raped and strangled. Among the dead was his ten-year-old daughter Wuane, killed in 1995, and Henry Bakers, a boy who had been in one of the same children's homes. He mutilated some of the bodies and returned to them.
Those named in the record are Monte Fiko, fifteen; Virginia Gysman, twenty-five; Mercia Papenfus, thirty-seven; Georgina Boniswa Zweni, forty-two; Katriena Claassen, twenty-two; and his own ten-year-old daughter, Wuane. Two more, a boy of fourteen and another young child, were never identified.
He was arrested in 1997 after a witness connected him to a missing boy, and he confessed at length to Micki Pistorius, the South African Police Service's profiler, in interviews that were later published. He was convicted and on February 23, 1998 received seven terms of life imprisonment.
He is one of a group of South African cases from the 1990s in which the police built a profiling unit under intense pressure and in which the interviewing was conducted by a psychologist rather than by detectives. His own account of his childhood, and of what he believed he was doing, comes from those interviews, and it is worth noting that the source for the interior of this case is the confession of a man who was already convicted on other evidence.