A shadowy figure seen on a roof above one of the Boston Marathon explosions has sparked conspiracy theories on Twitter.
The photo appeared on a Twitter account parodying musician Frank Ocean with the comment "Who's that guy on the roof??"
The post was quickly retweeted over 1900 times.
Many Twitter users asked why the image wasn't being investigated and why the media wasn't making an effort to help track the man down.
Twitter account @Urban_Supremacy attempted to stop further questions with a reply post.
"It was confirmed the man on the roof was just Boston Marathon security" he wrote.
No doubt the conspiracy theories will continue, however there appears to be little weight to this one.