LONDON -- Islamic State (ISIS) supporters in several European cities have Watch Bikini Pirates (2006)been reportedly located thanks to an online crowdsourcing effort.

Last Saturday, thousands of supporters of the group posted images of solidarity in honour of the group's spokesman, Abu Muhammad al-Adnani, who was rumoured to be releasing a long-awaited recording. 

The photographs, which showed European ISIS fans holding handwritten notes containing verses of the Quran, were originally posted on Telegram, a messaging app popular with supporters.

Their purpose was to create a buzz and demonstrate that the group had supporters across the continent.

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However, ISIS watchers found the pictures and shared them on Twitter, where Eliot Higgins, founder of citizen journalism website Bellingcat, started a crowdsourced effort to find the fanboys' location.

"They seemed like they'd be geolocatable so I shared them with my Twitter followers to see if they wanted to try, and pretty soon they started coming up with locations," Higgins told Mashable. 

Using landmarks and other geolocating methods, Higgins and Twitter users were able to find the location of four users in Germany, London, Paris and the Netherlands. 

"We examined four, those were ones I thought looked like they could be geolocated. So, for example, the Paris example it was a matter of IDing the Suzuki logo in the picture, looking up Suzuki shops in Paris, and checking Google Street View," he said. 

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Google Earth and Street View were used by a user who found an online map of advertising pillars in the German city of Munster to locate the ISIS supporter:

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Then it was the turn of the London supporter, who was pinpointed to a station in North London called Bruce Grove. 

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Local police tweeted it was aware of the ISIS supporter photo and an investigation was ongoing.

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Another was located by a member of the Bellingcat investigative team in Hoofddorp, a town near Amsterdam Schiphol Airport.

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A user even located the exact apartment building that the photographer was in:

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Higgins said local authorities the Netherlands are looking into it. 

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"Overall, the ISIS social media campaign backfired spectacularly, likely revealing information about multiple ISIS supporters in major European cities, including their residential locations and, perhaps with CCTV cameras, their identities," Higgins wrote in a post. 

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