The man, 55-year-old Nakoula Basseley Nakoula of the Los Angeles suburb of Cerritos, told his Coptic Christian bishop that he was not involved in the film, but media reports have widely linked his name to the video.
"The U.S. probation office in the central district of California is reviewing the case," said Karen Redmond, spokeswoman for the administrative office of the U.S. Courts in Washington, D.C., reached by phone from Los Angeles.
A source with knowledge of the case confirmed that the probation office was looking specifically into Nakoula's possible involvement in making the film for violations of the terms of his release.
The crudely made 13-minute English-language video, which was filmed in California and circulated on the Internet under several titles including "Innocence of Muslims," portrays the Prophet Mohammad engaged in crude and offensive behaviour.
The film sparked a violent protest at the U.S. consulate in the Libyan city of Benghazi in which the U.S. ambassador and three other Americans were killed on Tuesday. Protests have spread to other countries across the Arab and Muslim world.
For many Muslims, any depiction of the prophet is blasphemous. Caricatures deemed insulting in the past have provoked protests and drawn condemnations from officials, preachers, ordinary Muslims and many Christians in the Middle East.
Adding to the incendiary nature of the film was the fact that it had been promoted by a U.S.-based Egyptian Coptic Christian activist, Morris Sadek, who said his intent was to highlight discrimination against Egypt's Coptic minority. Copts have expressed fear the film could lead to retaliation.
Nakoula, whose home in Cerritos has been besieged by the news media and who could not be reached for comment, pleaded guilty to bank fraud in 2010 and was sentenced to 21 months in prison, to be followed by five years on supervised probation, court documents showed.
Nakoula was accused of fraudulently opening bank and credit card accounts using Social Security numbers that did not match the names on the applications, a criminal complaint showed. He was released in June 2011, and at least some production on the video was done later that summer.
NOT INVESTIGATING CONTENT
U.S. officials said authorities were not investigating the film project itself, and officials have said that even if it was inflammatory or led to violence, simply producing it cannot be considered a crime under U.S. law.
But the written terms of Nakoula's prison release contain behavior stipulations that bar him from accessing the Internet or assuming aliases without the approval of his probation officer.
A senior law enforcement official in Washington indicated the probation investigation relates to whether he broke either or both of these conditions. Violations could result in him being sent back to prison, court records show.
The film itself, posted on the Internet since July, has been attributed to a man whose name was given as Sam Bacile, which at least two people linked to the film have said was likely an alias.
A telephone number said to belong to Bacile and provided to Reuters by Sadek was later traced back to a person who shares the Nakoula residence.
Stan Goldman, a Loyola Law School professor, said that whether Nakoula might be sent back to jail over potential probation violations linked to the film, such as accessing the Internet, was a subjective decision up to an individual judge.
"Federal judges are gods in their own courtrooms, it varies so much in who they are," he said, noting such a move would be based on his conduct not on the content of the film.
A pair of attorneys visited Nakoula's home on Friday in Cerritos.
"I've been asked to consult with Mr. Nakoula regarding matters that I'm not at liberty to discuss," Steve Seiden, one of the attorneys, told reporters. He also asked media to leave.
In addition to the bank fraud conviction, Nakoula also pleaded guilty in 1997 to possession with intent to manufacture methamphetamine and was sentenced to a year in jail, according to Sandi Gibbons, a spokeswoman for the Los Angeles District Attorney's Office.
Nakoula told Bishop Serapion of the Coptic Orthodox Diocese of Los Angeles that he was not involved in the film, the bishop told Reuters.