Investigators have pinpointed two men as 'possible suspects' who were seen in images near the finish line of this week's Boston Marathon - moments before twin bombs there exploded, killing three and injuring about 180 others - a law enforcement official said.
A circular sent out Wednesday to federal and state agencies features the photos 'in an attempt to identify the individuals', who were described as being of 'high interest' to investigators.
The painstaking work to identify a bombing suspect from reams of Boston Marathon footage yielded a possible breakthrough as investigators focused on a man seen dropping off a bag, and then walking away from the site of the second of two deadly explosions.
The discovery of the image - found on surveillance footage from a department store near the finish line - emerged two days after the attack that left three people dead, wounded more than 170, and cast a dark shadow over one of this city's most joyous traditions.
Federal investigators involved in one of the largest manhunts in US history have revealed that the Boston marathon bombs that killed three people and injured more than 170 may have been made from pressure cookers packed with ball bearings and nails.
More than 1,000 law enforcement officials from 30 state and federal agencies have now been committed to tracking down whoever was responsible for Monday's twin blasts, the worst terror attack on US soil since 9/11.
image: © Lisamarie Babik