In 1989, Nieuwoudt along with Marthinus Ras and Wybrand du Toit were implicated in the killing of three black police officers Mbalala "Glen" Mgoduka, Amos Temba Faku, Desmond Daliwonga Mpipa and police informer Xolile Shepard Sakati in Motherwell. Nieuwoudt, Ras and du Toit planted a bomb in a car which blew up while the four police officers were driving. Nieuwoudt stated that the four police officers were killed because they had secretly joined the ANC. Niewoudt was sentenced to 20 years' imprisonment for the car bomb murder of what became known as the Motherwell Four. Nieuwoudt was awaiting the outcome for his amnesty application for the murder of the Motherwell Four at the time of his death in 2005 at the age of 54 in Port Elizabeth. Nieuwoudt died of lung cancer which had further spread to other organs in his body.