In a highly embarrassing episode which cast a shadow over the event, the unidentified interpreter has been accused of “signing gibberish” while a global audience watched the four-hour ceremony.
The man stood to the left of US President Barack Obama and other political leaders, seemingly interpreting their speeches.
However, as the footage was relayed, those familiar with South African sign language grew suspicious and it emerged that he was not communicating the words of the speakers.
The scandal, the latest indication of poor organisation at an historical occasion plagued by transport issues and a malfunctioning audio system, caused ructions in South Africa.
Minister Collins Chabane said the government was investigating the matter, but the administration was overwhelmed with work preparing for Mandela’s state funeral on Sunday.
Jackson Mthembu, a spokesman for the ruling African National Congress, said the man was not a party employee, but the government would answer all questions as the event was organised by them.
Bruno Druchen, the national director of the Deaf Federation of South Africa, said the man “was moving his hands around but there was no meaning in what he used his hands for”.
He and other sign language experts said the man was not signing in South African or American sign languages and could not have been signing in any other known sign language because there was no structure to his arm and hand movements.
Ingrid Parkin, principal of the St Vincent School for the Deaf in Johannesburg, said she received complaints from the deaf community from Canada to China and the man’s movements look “like he’s signing gibberish”.
“This man knows he cannot sign and he had the guts to stand on an international stage and do that,” Ms Parkin said.
Nicole Du Toit, an official sign language interpreter, said the man was an embarrassment. “It was horrible, an absolute circus; really, really bad,” she said.
It emerged yesterday that the same man signed at an event last year that was attended by South African president Jacob Zuma.
At that appearance, a deaf person in the audience videotaped the event and gave it to the federation for the deaf, which submitted a formal complaint to the ANC, said Mr Druchen.
Bogus sign language interpreters are a problem in South Africa, said Ms Parkin, as people who know a few signs try to pass themselves off as interpreters. “Organisations hiring them usually do not sign, so they have no idea that the people they are hiring cannot do the job,” she said.
Condolences from Royals
The Duke and Duchess of Cambridge have formally paid their respects to anti-apartheid hero Nelson Mandela by signing his book of condolence.
William and Kate travelled to South Africa House in central London yesterday to honour the former South African president.
The Princess Royal has already signed the book, as have Prime Minister David Cameron and
Labour leader Ed Miliband. A Kensington Palace spokesman said: “They wanted to pay their respects by signing the book.”
The Prince of Wales will represent the Queen at Mr Mandela’s funeral in Qunu, South Africa, on Sunday.
Leaders file past Mandela’s coffin
Nelson Mandela’s flag-draped coffin has been laid in state in the South African capital.
World leaders were the first to file past to pay their respects in the Pretoria amphitheatre where he was sworn in 19 years earlier as the country’s first black president.
Four junior naval officers in white uniforms kept watch.
Celebrities including singer Bono also paid their respects, as did FW de Klerk, the last president of white rule, who shared a Nobel Peace Prize with Mr Mandela for ending the apartheid era.