Niedermayer was kidnapped on 27 December 1973, at around 11 pm, from his home in West Belfast, by two IRA members who lured him outside his house on the pretext that they had accidentally crashed into his car. The abduction incident was witnessed by his two teenage daughters, who had answered the door to them, and by a neighbour who worked at the Grundig factory. The Government of the United Kingdom denied at the time that it had received any subsequent demands from the IRA in relation to the kidnapping, but several years later it was revealed that it had done so, and had briefly attempted to negotiate, with the IRA seeking the transferral from imprisonment in Great Britain to Northern Ireland of two of its members who had been jailed for involvement in a bombing campaign in London in 1973. However, the negotiations had ended abruptly from the IRA's side without explanation. In March 1980, the Royal Ulster Constabulary, acting on information received, located Niedermayer's body lying face down, with hands tied, and gagged, in a shallow grave at an illegal rubbish dump at Colin Glen. A forensic examination revealed that the cause of death had been severe injuries sustained to the head after being pistol-whipped with a handgun. His funeral took place at Dunmurry, and he was buried in the church's graveyard.
Eugene McManus and 42-year-old John Bradley were charged in connection with the crime. Bradley was originally charged with murder, but at his trial in 1981 he pleaded guilty to manslaughter, stating that he had accidentally killed Niedermayer whilst he was trying to escape. McManus pleaded guilty to withholding information about the crime and IRA membership. Bradley was subsequently sentenced to 20 years' imprisonment, and McManus to 5 years' imprisonment. Information later obtained by the Royal Ulster Constabulary revealed that the kidnapping operation had been set in motion by Brian Keenan, a former employee at the Belfast Grundig factory that Niedermayer had been the Director of, where Keenan, as a Trade Union representative, had had several confrontations with Niedermayer.
Subsequent events
Niedermayer's wife, Ingeborg, returned to Ireland in 1990, 10 years to the day of her husband's funeral, and booked into a hotel at Bray, County Wicklow, where she committed suicide by walking into the sea from an isolated beach. Niedermayer's two daughters, Gabrielle and Renate, both subsequently also committed suicide. Gabrielle's husband, Robin Williams-Powell, killed himself five years later. Gabrielle and Robin are survived by their two daughters, Tanya Williams-Powell and Rachel Robbins.
