How can I be so certain? Because I was the first to publish this photo.

"The first image of a gunman appeared to have been first released by what was purportedly an ISIL-related Twitter account." "ISIS tweeted out Michael Zehaf-Bibeau picture."

This photo was first published and identified on my 100 per cent news Twitter feed @Breaking3zero several hours before the traditional media got a hold of it.

But before I explain how the so-called ISIS-did-it theory was born, let me tell you the story behind this picture, How it landed on my computer screen and how I was able to identify it before sharing it with the world.

TWITTER

At around 2 p.m. EST on October 22, one of my followers informs me of its existence, asking me if this really is the shooter. At this point in time, information on the Ottawa attack is still very vague and contradictory.

My first reflex is to ask him about the source. He points to the responses to a tweet posted by the Ottawa Police. Not just any tweet. But a tweet asking the witnesses of the attack to share with the police any information allowing to identify the shooter. And there, among the first responses, is the photo of a man holding a rifle.

Don't bother looking, this tweet doesn't exist anymore. It was deleted almost instantly. Posted from an anonymous account, this picture found itself in the huge virtual haystack called Twitter.

I don't know who deleted it. The rate at which it was taken off makes me think that it was probably the author himself. Maybe he thought he was sending a private message. Maybe after talking to the police he followed their advice to take it down.

Whatever the reason, thanks to a screenshot, I find myself with a copy in hand in the early afternoon.

INVESTIGATION

Out of the question to publish it at this point. Without any research, and no certitude. And also out of the question to publish it prematurely, while there is still chaos in Ottawa, and the shooter might have accomplices.

Like a lot of journalists I have my sources, and I decide to send them the photo to get their feedback. In the meantime, I try to identify other elements to confirm its authenticity.

I start with the weapon itself. A Winchester. Three possible models. 1886, 1873, 1892. In any case, a very specific weapon. A hunting rifle. Not a semi-automatic. Not an automatic.

The first witness accounts coming in from the attack within the Parliament mention a rifle. And then there is the AUDIO recording. We hear the suspect shooting before the security personnel respond. While they spray continuously, he fires shot by shot. Just like a Winchester.

Then there is the scarf. Some witnesses of the shooting precisely described the suspect as wearing a "muslim-style scarf." Although this description is rather vague, the picture shows a man whose face is partially covered by a black-and -hite keffieh similar to those worn by the activists defending the Palestinian cause in the eighties.

Finally, there is the umbrella.

Its white handle shows under the suspect's right hand. The rest on the left hand side near his shoulder. It is thanks to this accessory that the shooter was able to hide his weapon, leave his vehicle and advance all the way to the monument without drawing attention.

If the information from one of my sources is correct, this is confirmed by the surveillance footage.

SOURCE

The weapon, the keffieh, the umbrella. Three pieces of evidence indicating the authenticity of the photo.

And as I am in the process of corroborating the background of the photo with that of the Ottawa monument, one of my sources gets back to me.

Only minutes earlier, a photo started circulating amongst Canadian security forces. Not this one, but a different one.