The man accused of faking sign interpretation while standing alongside world leaders at Nelson Mandela's memorial service on Tuesday said on Thursday that he was suffering from hallucinated at the time.
Thamsanqa Jantjie said he suffers from schizophrenia and has been violent in the past.
Jantjie his hallucinations began while he was interpreting and that he tried not to panic because there were armed policemen around him.
He said he saw "angels" entering the stadium and realised there was a problem: "Sometimes I will see things that chase me. I was in a very, very difficult position."
When shown video footage of him interpreting at the Mandela memorial service, Jantjie said he didn't remember any of it.
Jantjie, who stood gesticulating three-feet (1 meter) from Obama and others in the globally-broadcast ceremony, apologised for his performance that has been dismissed by many sign-language experts as gibberish.
Government minister Collins Chabane said officials were looking into the matter.
"The government will report publicly any information it may establish but wishes to assure South Africans that we're clear in defending the rights and dignity of people with disabilities," he said.
Government officials have tried to track down the company that provided Jantjie but have not been able to locate them.
On the day of the ceremony Jantjie said he was due to get a regular six-month mental health check-up to determine whether the medication he takes was working and whether he needed to be kept at a mental health facility for treatment.
He said he did not tell the company that contracted him for the event that he was due for the checkup, but said the owner of SA Interpreters in Johannesburg was aware of his condition.
Jantjie's comments raise serious security issues for Obama, other heads of state and UN Secretary-General Ban Ki-moon who made speeches at FNB Stadium in Soweto.
Many of them, including Obama, stood one yard (meter) away from Jantjie.
Jantje had already taken part in other official events, standing next to South African President Jacob Zuma at the ANC elective conference in 2012.