He made waves with his arms, touched his forehead and reached out with an embracing motion. And as the official interpreter for the deaf watching the Nelson Mandela memorial event Tuesday, he stood right behind the world’s most powerful leaders, including President Obama.

And he was a fake, advocates for the deaf say.

Web sites and radio shows here were flooded with condemnations of the African National Congress-led government and the organizers of the memorial at FNB Stadium in Soweto for failing to figure out whether the man was simply waving his arms around.

“Please get RID of this CLOWN interpreter, please!” Bruno Peter Druchen, head of the Deaf Federation of South Africa, tweeted during the memorial.

“ANC linked interpreter on stage is causing embarrassment amongst deaf ANC supporters. Please get him off,” added Wilma Newhoudt, a deaf member of the South African Parliament and vice president of the World Federation of the Deaf.

But the man remained on stage, and on Wednesday, his performance became the focus of a new storm of criticism. People who phoned an afternoon radio call-in show said the situation showed inept hiring, insensitivity to the deaf and a serious security lapse on the part of event organizers. And, they said, it marred the solemn event by distracting attention from Mandela and the world leaders who came to pay tribute to him.

On Thursday, the Johannesburg Star reported that the man, Thamsanqa Jantjie, said in an interview that he was suffering from schizophrenia and that he had lost concentration and started hearing voices during the event. He said that made it hard to hear the speeches and interpret but that he couldn’t just leave so he stayed on. “There was nothing I could do. I was alone in a very dangerous situation. I tried to control myself and not show the world what was going on. I am very sorry, it’s the situation I found myself in,” Jantjie, 34, told the Star.

He said he works for a company called SA Interpreters and that they told him on Monday that he would interpret at the memorial service. “Life is unfair. This illness is unfair. Anyone who doesn’t understand this illness will think that I’m just making this up,” Jantjie told the Star.

In other interviews, however, Jantjie defended his performance at the Mandela memorial. Asked if he was happy with it, he told Johannesburg’s Talk Radio 702: “Absolutely, absolutely. I think that I’ve been a champion of sign language.”

Hendrietta Bogopane-Zulu, deputy minister of women, children and people with disabilities, told a news conference that Jantjie, 34, “was not a professional.” She said he was paid far less than a professional sign language interpreter would have earned and that the company that allegedly employed him “vanished into thin air.”

Bogopane-Zulu added: “It’s a clear indication that over the years they have managed to get away with this. They have been providing substandard sign language interpreting services to many of their clients.”

She apologized to deaf people who were offended and were denied translations of the memorial speakers’ remarks.

According to the Associated Press, Collins Chabane, one of South Africa’s two presidency ministers, said the government was investigating and “will report publicly on any information it may establish.”

The agency also reported that an address and phone number that Jantjie provided for his company in an interview turned out to be false.

White House officials directed questions about the interpreter to the South African government but gave no indication that there were concerns about Obama’s security arising from the discovery.

“I think the point is that he apparently was not translating him into anything but was enjoying the opportunity to be on the stage,” Josh Earnest, the principal deputy White House press secretary, said Wednesday at the daily briefing. “It would be a shame if a distraction about an individual who’s on stage in any way detracted from the importance of that event and the importance of President Mandela’s legacy.”

It was the latest controversy in a week devoted to remembering Mandela. President Jacob Zuma was booed by the crowd at the stadium, rain kept “overflow” stadiums largely empty, and lines of people waiting to see Mandela’s body in state Wednesday snaked their way through a hot, jam-packed parking lot while a single security checkpoint slowed progress.

Many viewers of Tuesday’s event noticed that the man was using the same gestures over and over again. Druchen tweeted that the man “is not using sign language at all.”

Sign language interpreter Francois Deysel tweeted, “please can someone ask the interpreter to step down from stage, it is embarrassing and making a mockery of our profession.”

Video clips show that this wasn’t the man’s first performance. He was the interpreter at the ANC’s Mangaung policy conference in the Free State last year. He interpreted the controversial song “Shoot the Boer” led by Zuma during his election campaign. When Zuma said people would run, the man pumped his arms up and down. Often, the man’s gestures were the same as Zuma’s. (Boer is a term for white Afrikaners.)

Druchen observed that the phony interpreter “knows that the deaf cannot vocally boo him off. Shame on him!”

Interpreters are not unusual in multilingual South Africa, where large groups of people speak English, Afrikaans, Zulu, Xhosa or other African languages. Druchen recommended that signing be made the country’s 12th official language.

Sign language interpreters and others in the United States and around the world also expressed outrage at the incident.

“We, along with many other organizations, are disappointed with the process that selected the interpreter that was shown on camera for the Mandela service, and feel that a great disservice was done to both the South African signing community, and the international signing community,” the Registry of Interpreters for the Deaf, based in Alexandria, Va., said in a statement.

The World Association of Sign Language Interpreters, based in Australia, said: “This situation stresses the need for continued public education about the formal training required to be a qualified sign language interpreter and the need for interpreter and deaf associations to collaborate on pressing governments for standards.”

The National Association of the Deaf, based in Silver Spring, Md., said interpreters must be vetted.

“Each country has its own national sign language and sometimes even regional sign languages,” the association said. “In the United States, we use American Sign Language (ASL) while in South Africa, most people use South African Sign Language (SASL), which is distinct and uses different signs than ASL. We, at the NAD, cannot assess the qualifications or fluency or lack thereof of the interpreter in this video, but are informed by the South African deaf and hard of hearing community that this interpreter is not legitimately interpreting in SASL.”

One expert in the United States who reviewed a video of the event said problems with the purported interpretation were easy to see.

“When I watch him, he appears to be doing a lot of repetitive hand motion. It doesn’t look like any natural sign language to me,” said Melanie Metzger, head of the department of interpretation at Gallaudet University, a prominent school for the deaf and hard of hearing in Washington, D.C. “What he’s doing is not matching the speaker. He’s not interpreting the speaker.”

Metzger said another tipoff was that the man onstage used minimal facial expressions. Authentic interpreters around the world, she said, make extensive use of their eyebrows, cheeks and other parts of the face to communicate in sign language.