The man accused of faking sign language interpretation at Nelson Mandela's memorial service in Johannesburg is apologizing and saying he may have suffered a schizophrenic episode while on stage.

In an interview with The Associated Press Thursday, Thamsanqa Jantjie said he has schizophrenia and was trying his best to control himself as he heard voices throughout the three-hour memorial event.

"What happened that day, I see angels come to the stadium ... I start realizing that the problem is here. And the problem, I don't know the attack of this problem, how will it come," Jantjie told AP.

He added that he was once hospitalized for his illness in a mental health facility for more than one year, and that he sometimes gets violent during episodes in which he sees things chasing him. He did not describe his violent episodes.

Jantjie said he was "in a difficult position" while he was hearing voices during the memorial, as he knew there were armed police all around him and he didn't want to start panicking.

Several sign-language experts have complained that Jantjie’s signing at the memorial was gibberish, not American Sign Language nor South African signing. South Africa's leading deaf association denounced Jantjie as a fake and said he was simply making up gestures.

Jantjie told South Africa's The Star newspaper that he works for an interpreting company called SA Interpreters. He did not describe his sign language qualifications nor did he address the allegations that he faked the sign language.

AP says it was able to contact a representative for SA Interpreters Thursday, but the rep declined to comment. The Reuters news agency says its own attempts to track down the company were unsuccessful.

In an interview with Talk Radio 702, Jantjie noted that he had signed at several other high-profile events and questioned why his signing abilities had never been challenged before.

"If I was interpreting not right, why it was not been picked up on by that time? You must remember you are talking about an interpreter that's been interpreting through those years. And if I was interpreting wrong all these years, why should it become an issue now?" he said in broken English.

Jantjie's statements raise serious concerns about the security measures that were in place during the memorial in Johannesburg's 95,000-seat Soccer City stadium, where Prime Minister Stephen Harper, UN Secretary-General Ban Ki-moon, and several other heads of state were in attendance.

South Africa's Deputy Minister of Women, Children and People with Disabilities held a news conference late Thursday to announce that "a mistake happened" in the hiring of Jantjie.

Hendrietta Bogopane-Zulu said government officials have tried to track down the interpreting company, but the owners "have vanished into thin air."

She apologized to deaf people who watched the event and who were offended by Jantjie's incomprehensible signing. She said an investigation is under way to determine how Jantjie was hired and what vetting process he underwent for his security clearance.

The deputy minister said the translation company offered sub-standard services. She declined to say who in South Africa's government was responsible for contracting the company that provided the translator.

"It's an interdepartmental responsibility," she said. "We are trying to establish what happened."

With reports from The Associated Press