BOSTON, MA-The FBI has released images showing the remains of a pressure cooker, part of one of the bombs that exploded at the Boston Marathon Monday leaving 3 dead and 176 wounded, 17 critically.
A 'worldwide investigation' is now underway, according to the FBI.
They are appealing to the public for tips and pictures that might yield clues.
So far investigators have determined the bombs were contained in 6-liter pressure cookers and placed in black duffle bags, then left on the ground among the crowds watching runners cross the finish line.
Massachusetts Governor Deval Patrick has cleared up an initial misconception, saying no unexploded bombs had been found.
"It's important to clarify that two and only two explosive devices were found yesterday. All other parcels in the area of the blast have been examined but there were no unexploded bombs." said Patrick.
It is believed the bombs were placed near the finish line well after the race began, and after a second security sweep.