The man whose amateur video of a Paris police officer's cold-blooded murder shocked the world now regrets sharing the footage online, saying he never expected it to be broadcast so widely.

Engineer Jordi Mir told The Associated Press Sunday he posted the video out of fear and a "stupid reflex" fostered by years on social media. "I was completely panicked," he said in an exclusive interview across from the Parisian boulevard where the officer was shot to death by terrorists Wednesday morning.

The short film immediately became the most arresting image of France's three-day-long drama, which began with a mass killing at the headquarters of satirical weekly Charlie Hebdo and ended Friday with the death of four hostages and the three terrorists in two separate shootouts. "I had to speak to someone," Mir said. "I was alone in my flat. I put the video on Facebook. That was my error."

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Mir said he left the video on Facebook for as little as 15 minutes before thinking the better of it and taking it down. It was too late. The footage had already been shared across the site and someone uploaded it to YouTube. Less than an hour after Mir removed the video from his page, he was startled to find it playing across his television screen.

In its unedited form, the 42-second film shows two masked gunmen — brothers Cherif and Said Kouachi — as they walk toward a prone police officer, later identified as 42-year-old Ahmed Merabet. "You want to kill us?" one of the brothers says as he strides toward the wounded officer. "No, it's OK, boss," Merabet says, raising his hand in an apparent plea for mercy. Then he's shot in the head. The video unleashed a worldwide wave of revulsion.

British tabloids described it as "shocking" and "sickening." France's Le Figaro ran a still from the footage on its front page over a caption which read "War." CNN's Randi Kaye called it "an unforgettable image forever associated with this horrible attack."

The iconic nature of the imagery — rebroadcast again and again — has anguished Merabet's family. His brother Malek told journalists Saturday: "How dare you take that video and broadcast it? I heard his voice. I recognized him. I saw him get slaughtered and I hear him get slaughtered every day."

A frame grab taken from a footage made available and posted by Jordi Mir, a local resident, on January 7, 2015 shows hooded gunmen aiming Kalashnikov rifles towards a police officer, before shooting him dead after leaving the office of the satirical weekly newspaper Charlie Hebdo. A huge manhunt for two brothers suspected of massacring 12 people in an Islamist attack at a satirical French weekly zeroed in on a northern town on January 8 after the discovery of one of the getaway cars. JORDI MIR / AFP - Getty Images

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Family of dead policeman #CharlieHebdo condemn media publication of video+pic showing his execution http://t.co/nqwM70vR5Y cc @guardian — Marc Menichini (@marcmenichini) January 10, 2015

— The Associated Press