Kruger was born in Wales and was adopted by Afrikaner parents; he was part of the conservative National Party government which championed apartheid. He was responsible for the banning of Black Consciousness Movement leader Steve Biko; when Biko died in police custody, the police claimed that Biko had died during a hunger strike. This account was challenged by the liberal white South African journalist Donald Woods, a personal friend of Biko. Kruger's response to Biko's death was: "Dit laat my koud." ("It leaves me cold."). Kruger later began to recant his earlier statements, while claiming that Biko had authored pamphlets calling for "blood and body in the streets." Woods came under increasing scrutiny for his articles, and finally, following the publication of an article calling on Kruger to resign, he was banned under direct orders from Kruger. Not long afterwards, Woods and his family fled the country for a life of exile in England.
In response to international pressure, the South African government ordered an inquest to investigate the cause of Biko's death; the presiding magistrate concluded that Biko had died of brain damage caused by head injury; however, no one was held responsible for, or prosecuted for, Biko's death. Even so, it was the end of Kruger's career. Having decided that his performance had severely compromised the country's credibility abroad, the government ordered him to resign, and he lost not only his cabinet post, but his membership in the ruling party, as well. In 1982, Kruger joined the Conservative Party of Andries Treurnicht to protest the "racial reforms" of the Botha Government. Kruger spent the rest of his life in political obscurity.
Kruger was married to Susan Kruger after whom the Robben Island ferry the Susan Kruger was named in 1977.
In the film Cry Freedom (1987), which was based on Woods's role in the anti-apartheid struggle, Kruger was portrayed by English actor John Thaw.