US authorities have questioned the alleged brains behind the film that has inflamed much of the Muslim world by lampooning the Prophet Mohammed, but quickly released him.
Nakoula Besseley Nakoula was "given a ride" from his southern California home to the interview in the early hours of Saturday, with investigators seeking to establish if he broke the terms of his probation over a bank fraud conspiracy, Los Angeles County Sheriff's Department spokesman Don Walker says.
A man reportedly later emerged from the police station wearing a coat, hat, scarf and glasses.
The anti-Islam film - entitled Innocence of Muslims on its 14-minute YouTube trailer - was produced by a US religious group called Media for Christ and believed to have been directed by a pornographer.
Nakoula, a US-based Egyptian Coptic Christian, has previously admitted uploading the trailer on the internet.
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In 2010 he was convicted of defrauding US banks by opening false accounts and passing bad cheques, court documents show, and he served one year before being released on probation.
As part of his release terms, he was forbidden from using computers or the internet for five years and ordered to pay more than $US790,000 ($A752,416.78) in restitution.
His questioning on Saturday did not take long, Walker said, though the outpouring of anger about the film persists - as do inquiries into its origin.
It was directed by 65-year-old Alan Roberts, an industry veteran whose prior oeuvre was dominated by schlock soft porn and hammy action with titles like Young Lady Chatterley II and Karate Cop, according to website Gawker.
Gawker interviewed members of the cast of Innocence of Muslims, who say they were duped into appearing in what they thought was a fictional epic, only to discover their lines had been dubbed over with anti-Muslim propaganda.
Roberts' casting call lists the leading roles as George, Condalisa and Hillary. But in the finished version the script was doctored to make them represent the prophet and key figures from the Koran.
The film was promoted by a network of right-wing Coptic and Evangelical Christians with a radical anti-Muslim agenda, such as Egyptian American provocateur Morris Sadek and Terry Jones, a Florida pastor notorious for publicly burning a Koran.
And, acting as "consultant" was Steve Klein, a Vietnam veteran and founder of Courageous Christians United who is notorious for protests outside mosques and Mormon temples and who told Agence France-Presse on Saturday he helped the moviemakers.
The film itself does not appear to have broken any US laws but Nakoula may have breached the rules governing his conditional release from prison.
"The matter is under review," said a spokesman for the Administrative Office of the US Courts.
This week saw Nakoula move from anonymous petty criminal to being a key figure in a global furor that has triggered mass protests in Muslim-majority countries in North Africa, the Middle East, Asia and elsewhere, and seen several US diplomatic missions attacked.
Reporters and police are camped out outside his house in Cerritos outside Los Angeles.
He gave an interview to Radio Sawa, a US-government station that broadcasts in Arabic.
"I am the one who leaked the 14 minutes and put it on the internet and I am thinking about releasing the full film. Nobody manipulated my film," he said.
The clip on YouTube was picked up by Egyptian television.
