While Feds go in to overdrive to crack the Boston Marathon terror attacks pix of mystery man on the roof has folks spooked.

Amongst the grim and disturbing imagery of the Boston Marathon bombing, images  taken by spectator Dan Lampafriello shows a man walking on the roof of a building near the site of the second detonation.

As The ENQUIRER reported  two bombs were detonated about 12 seconds apart at 2:50 p.m. near the race's finish line.

 According to Yahoo News, the phrase “Boston Marathon roof” was now trending on Twitter after a rogue blogger uploaded it.  

"Who's the guy on the roof? He's not reacting to the detonation," one Twitter user queried.

"What is this thing about some guy on a roof? Mystery man? I bet that's the guy!" another user postulated.

The identity of the shadowy figure is not known, nor is it clear if he had anything to do with the  attack.

"That man on the roof on the Boston marathon photo is creeping me out," one user tweeted.