LOS ANGELES - A California man linked to an anti-Islam film that sparked violent protests across the Muslim world was questioned on Saturday by authorities investigating possible violations of his probation for a bank fraud conviction.

Nakoula Basseley Nakoula (C) is escorted out of his home by Los Angeles County Sheriff's officers in Cerritos, California Sept 15, 2012. [Photo/Agencies]

Nakoula Basseley Nakoula, 55, a Coptic Christian, was voluntarily interviewed by federal probation officers at a sheriff's station in the Los Angeles suburb of Cerritos and left about 30 minutes later, said Steve Whitmore, a spokesman for the Los Angeles County Sheriff's Department.

The crudely made 13-minute English-language movie, filmed in California and circulated on the Internet under several titles including "Innocence of Muslims," mocks the Prophet Mohammad and portrays him as a buffoon.

The film helped generate a violent protest at the US consulate in the Libyan city of Benghazi during which the US ambassador and three other Americans were killed on Tuesday. US officials said they believe militants used the protest as cover to carry out an armed assault on the diplomatic compound and a building that was supposed to be a safe house.

Protests have spread to other countries across the 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.

US officials have said authorities were not investigating the film project itself, and that even if it was inflammatory or led to violence, simply producing it cannot be considered a crime in the United States, which has strong free speech laws.

An attorney for Nakoula did not return phone calls and a representative for the US Probation Office had no comment on the outcome of Nakoula's questioning by officers.

Nakoula was ushered out of his home shortly after midnight and into a waiting car by sheriff's deputies, his face shielded by a scarf, hat and sunglasses.

"He was never put in handcuffs ... It was all voluntary," said Whitmore, who added that Nakoula would not immediately return to his home. 

A Muslim protester hits a caricature of Florida pastor Terry Jones with her footwear during a protest, against a US-made film they consider blasphemous to Islam, near the US consulate-general, in the southern Indian city of Chennai Sept 15, 2012. [Photo/Agencies]

Bank fraud conviction

Nakoula, whose name has been widely linked to the film in media reports, 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.

He 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 the film was produced later that summer.

The terms of Nakoula's release restrict him from accessing the Internet or assuming aliases without the approval of his probation officer.

A senior law enforcement official in Washington has indicated the probation investigation relates to whether Nakoula broke one or both of these conditions.

A source with knowledge of the case has said the probation office was looking specifically into Nakoula's possible involvement in making the YouTube film in violation of the terms of his release.

Any probation violation could result in him being sent back to prison, court records showed.

Clips of the film posted on the Internet since July have been attributed to a man by the name of Sam Bacile, which two people linked to the film have said was likely an alias.

A telephone number said to belong to Bacile was given to Reuters by US-based Coptic Christian activist Morris Sadek who said he had promoted the film. That phone number was traced back to a person who shares the Nakoula residence.