In these combination pictures Barack Obama delivers a speech next to a sign language interpreter during the memorial service for Nelson Mandela.

The sign language interpreter at Nelson Mandela's funeral has said a schizophrenic episode was to blame for accusations that he was an imposter who gesticulated nonsense during the entire service.Thamasanqa Jantjie was branded as a scurrilous fake after members of South Africa's deaf community said his signing at Tuesday's memorial ceremony had amounted to nothing more than "flapping his arms around."In an interview Thursday with the Johannesburg daily, The Star, Jantjie put his behaviour down to a sudden attack of schizophrenia, for which he takes medication.He told the newspaper that he lost concentration, started hearing voices and hallucinating."There was nothing I could do. I was alone in a very dangerous situation," he said."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," he added.Jantjie's efforts at the memorial service, during which he translated eulogies by US President Barack Obama among others, triggered outrage in the deaf community and prompted a government investigation.Cara Loening, director of Sign Language Education and Development in Cape Town, labelled him a "complete fraud" whose signing looked like someone "trying to swat a few flies away from his face and his head".Asked why he didn't just leave the stage, Jantjie said that, given the historic importance of the event, he felt compelled to stay even though he could not hear or concentrate properly."Life is unfair. This illness is unfair," he said."Anyone who doesn't understand this illness will think that I'm just making this up," he added.Attended by nearly 100 sitting and former heads of state or government, the speeches at Mandela's memorial were supposed to be interpreted into sign language for deaf viewers.Jantjie's signing appeared at odds with that of the public broadcaster's signer, who was shown in a small insert box on SABC television screens.The interview with The Star did not address the fact that Jantjie's competence had been called into question before the memorial furore erupted.

The South Africa's Translators' Institute said they already had reservations about Jantjie, who had previously signed at the ruling ANC party's events, including its centenary anniversary last year.The institute's chairman Johan Blaauw said there had been complaints over his work on those occasions as well, but the ruling party took no action.