During the worst days of apartheid, South Africa’s white-led police force terrorized Black people with a brutal interrogation tactic that involved suffocating them, often with plastic bags.

After apartheid, South Africa adopted a constitution that explicitly outlawed such torture methods and signed international treaties committed to prevent it.

But a New York Times analysis of government data has found that, three decades after apartheid, the police in South Africa continue to use the same suffocation method — known as tubing — when interrogating suspects.

From 2012 to 2023, an average of three people per week filed complaints that the police had tubed them during interrogations, according to the analysis done by The Times in collaboration with Viewfinder, a South African journalism nonprofit that reports on police misconduct.

The findings represent a striking contradiction. A government led by freedom fighters who helped liberate Black South Africans from apartheid is now overseeing a police force that tortures them, betraying a promise not to repeat the atrocities of the country’s former oppressors.

“I’m really shocked because it brings back very, very, very bad memories,” said Khulu Mbatha, a veteran of the liberation party, the African National Congress, when told of the findings. “The leadership of the A.N.C., when they came to power in 1994, made it clear: No soul should be subjected to that.”