US police have visited the home of a California resident who admitted involvement in the film which sparked anti-US riots in the Arab world.
Nakoula Basseley Nakoula, 55, of Cerritos, California, is said to be a Coptic Christian of Egyptian origin.
He told the Associated Press on Wednesday that he was the manager for the company that produced the film.
But he has denied being “Sam Bacile”, credited as the writer and director of the film.
However, the Associated Press says police now believe Mr Nakoula was in fact the director of Innocence of Muslims.
Police were photographed entering and leaving Mr Nakoula’s house on Wednesday night.
The front door of the property is said to resemble a door used in the controversial film.
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Sam said no this is not your fault. He said, you tell the world that I did this. That I wrote this script”
Cindy Lee Garcia
A spokesman for the sheriff’s department in Cerritos refused to confirm Mr Nakoula’s link to the film, telling the BBC: “All we are doing is providing safety for anybody that needs it.”
The obscure film mocked Muslims and the Prophet Muhammad. It was shown to tiny audiences in Los Angeles in June, but has since achieved notoriety online.
A clip of the film dubbed into Arabic has been blamed for sparking protests at US missions in Egypt, Libya, and Yemen.
US Ambassador J Christopher Stevens and three other Americans died in an attack on the diplomatic mission in Benghazi, Libya.
Unconfirmed reports suggest the Libya attack could have been planned ahead of the appearance of the film.