JOHANNESBURG (AP) — A South African deputy Cabinet minister says "a mistake happened" in the hiring of a sign language interpreter for the Nelson Mandela memorial service who experts say was signing gibberish on stage next to world leaders.

Hendrietta Bogopane-Zulu said Thursday that government officials have tried to track down the company that provided Thamsanqa Jantjie but that the cowners "have vanished into thin air." Deputy Minister of Women, Children and People with Disabilities Bogopane-Zulu apologized to deaf people offended around the world by what they say was Jantjie's incomprehensible signing.

She says an investigation is under way to determine how Jantjie received a security clearance.