Speaking to the Associated Press from hiding, the man said he is an Israeli-born Jewish writer and real estate developer in California. The purported filmmaker said he wanted to make a provocative movie to help expose Islam's flaws to the world.
But there is no public record of a person with that name and profession in California, and Israeli officials say there is no record either of his being a citizen of Israel.
Steve Klein, a Christian activist who says he was a consultant for the movie, told reporters that Sam Bacile is a pseudonym and that the filmmaker is not Israeli and probably not even Jewish. He said Bacile contacted him because Klein leads anti-Islam protests outside mosques and schools.
Klein also said about 15 people worked on the film, all of them American citizens, but some of them are from Syria, Turkey, Pakistan, Egypt and elsewhere.
He said Bacile is concerned about the safety of his family, which he said is in Egypt.
It is not clear how many people saw the two-hour movie, but the 14-minute trailer in English and Arabic, posted on YouTube, sparked anger among ultra-conservative Muslims in Egypt, Libya and elsewhere. It shows the Muslim prophet as a fraud, a womanizer and a terrorist.
During a protest outside the U.S. consulate in Benghazi Tuesday, unknown gunmen killed U.S. Ambassador to Libya Christopher Stevens and three other U.S. staff members.
The man calling himself Bacile was sorry about the ambassador's death, but he blamed the security system at the U.S. mission.