)
US investigators appear to have spotted a possible suspect in the Boston Marathon bombings through footage from surveillance videos that shows the individual allegedly carrying and planting the bomb near the finish line of the popular sporting event.
A report in the 'Boston Globe' quoted an official briefed on the bombing investigation as saying that authorities have an image of a suspect carrying, and perhaps dropping, a black bag at the second bombing scene on the route of the marathon in the heart of the city.
Investigators are "very close" in the investigation, the official added.
Investigators say a surveillance camera located at a huge luxury store directly across the street from the location of the blast provides a clear video of the area.
The camera from the luxury store is the "best source of video so far," said Dot Joyce, a spokeswoman for Boston Mayor Thomas M Menino.
Two bombs ripped through the crowds and runners at the Boston Marathon, killing three persons and injuring over 180.
As the investigation into the bombing entered its third day, conflicting reports emerged about the suspect being identified and arrested.
The FBI and Boston police have denied media reports that an arrest in the case has been made and have cautioned the news media to be cautious in their coverage of the blasts.
Investigators have found a piece of lid of one of the pressure cookers believed to have been used as the explosive device on a rooftop near the blast.
One of the two bombs that exploded near the finish line of the Boston Marathon is believed to have been hidden in a pressure cooker inside a backpack, the FBI said in a joint intelligence bulletin.
The device also had fragments that may have included nails and ball bearings, the agency said.
The second bomb was also hidden in a metal container, but it was not clear whether it too was in a pressure cooker, the FBI said.
Special agent in charge of FBI's Boston Division Richard DesLauriers said that several "physical items" related to the bombings have been recovered from the blast site and those have been sent to the FBI's Laboratory in Virginia where specialised examiners would reconstruct the device and determine its makeup and components.
Among items partially recovered are pieces of black nylon which could be from a backpack - fragments of nails possibly contained in a pressure cooker device.
DesLauriers said both of the explosives were placed in a dark-coloured nylon bag or backpack.
The FBI has received more than 2,000 tips giving possible clues about who could be behind the blasts and many of those tips have been reviewed, analysed, and vetted by the agency.
