The FBI has interviewed a US man after he admitted faking a video that appeared to show him being beheaded while held hostage in Iraq.
Mr Vanderford said he had made the video at a friend's house
The FBI said it was still considering whether 22-year-old Benjamin Vanderford had broken any law.
Mr Vanderford said he filmed his own mock execution in a friend's garage to show how the media could be fooled.
The apparent execution was widely reported after the footage appeared on a website used by Islamic militants.
The video was reported to have been made by militants linked to top al-Qaeda suspect Abu Musab al-Zarqawi.
Mr Zarqawi's group has released tapes of previous hostage beheadings, but doubts were quickly expressed about this purported killing.
The dark images of the faked video showed a man dressed in a plain T-shirt, sitting on a chair with his hands behind his back.
"I have been offered for exchange for prisoners here in Iraq," he says.
"We need to leave this country right now. If we don't, everyone is gonna be killed in this way."
After that, a body is shown on the floor with a knife apparently cutting at the neck.
Mr Vanderford told the BBC World Service he did not send the video to anyone, but made it available on internet share networks. The "people of the world" did the rest, he said, and the video found its way to Arab television stations on Saturday and then a US news agency.
"I thought about the nature of the American media and how easily it can be manipulated," he said on the World Today programme.
Once the Arabic news channel al-Jazeera broke the story, it was picked up by the Associated Press news agency "and then suddenly it was the 'truth', when actually no physical evidence has been recovered", he said.
Mr Vanderford, who lives in San Francisco, said he decided to make the video after watching some of the coverage of prisoner executions in Iraq.
He said the videos tended to be of low quality with bad camera angles.
"I am in no way trying to denigrate any lives that have been lost, but my first thought was this could be faked by someone," he said.
Mr Vanderford said he believed "anyone could do this for political gain" and he thought he should bring attention to that.
3 August: Turkish driver Murat Yuce shot dead
29 July: Pakistanis Azad Hussein Khan and Sajjad Naeem's dead bodies are shown on video
14 July: Georgi Lazov, 30, Bulgarian truck driver is beheaded
29 June: Keith Maupin, 20, US soldier is reportedly killed (not confirmed)
22 June: Kim Sun-il, 33, South Korean translator beheaded
11 May: Nick Berg, 26, US businessman beheaded
14 April: Fabrizio Quattrocchi, 36, Italian security guard shot dead
FBI spokeswoman LaRae Quy said the agency initially became involved while trying to verify whether anyone had been beheaded.
She said Mr Vanderford had admitted making the hoax video.
"We are collecting all the facts at this point in this process and we will pursue any and all legal avenues," she said.
"We are trying to determine what laws may have been broken by such an act."
Militants have seized scores of foreign hostages in Iraq, usually demanding the withdrawal of foreign troops.
An American, a South Korean and a third man, said to be a Bulgarian, have been shown on videos being beheaded.