An American flag waves at site of Boston atta
An American flag waves at site of Boston attaReuters

American FBI personnel may have tracked down at least one of the terrorists behind the attack on the Boston Marathon, but no arrests have yet been made as the probe continues into a deadly twin bombing that ripped through the finish line Monday at Copley Square.

Authorities said they may have zeroed in on a man they believe may have planted the bombs, after having identified him in footage from the event, The New York Times reported late Wednesday.

The suspect’s name has not been released and he had not yet been arrested by early Thursday morning, according to media reports.

Several video clips showed the man, along with several others “of interest” due to their proximity to the scene and/or because of what they appear to be doing on the footage, a senior law enforcement official told reporters.

But at least one man is seen dropping a bag, numerous viewers agreed, the official said.

The U.S. Federal Courthouse in Boston meanwhile became a scene of utter chaos at midday due to a bomb scare, with hundreds of journalists and other spectators scrambling late in the day Wednesday as marshals moved to clear the area.

An official who declined to be named told reporters that authorities have an image of a suspect carrying, and perhaps dropping a black bag at the scene of the second bombing on Boylston Street, outside the Forum restaurant. The official added that investigators are “very close” to closing in on a suspect in the probe.

“Someone knows who did this,” Richard Deslauriers, special agent in charge of the Boston FBI office, told reporters. He urged the public to contact authorities if they had any tips to offer, pointing out that someone might have heard a bomber testing explosives in a remote area. He also asked if anyone had seen someone carrying a heavy black bag to the marathon on Monday, noting the bag would have had to have been heavy due to the contents of the bombs. 

Officials have urged the public to keep sending in videos and photographic evidence they might have, that could provide clues to who might have been behind the bombing.

“We want people to come and go. We want you to live your life,” Boston Police Commissioner Edward Davis said at a briefing. But, “we want you to be vigilant... give us a little room in the Copley Square area,” which he called “the most complex crime scene in the history of the department.”

A circuit board believed to have been used to detonate the bombs has been recovered from the scene, investigators told reporters, along with components of the bombs. 

FBI officials have said the bombs appeared to have consisted of two 6-liter pressure cookers packed with shrapnel consisting of nails, metal B-Bs and ball bearings, placed in black nylon duffel bags.

The bombs exploded right along the finish line of one of the most famous marathons in the world, about 12 seconds apart. A third bomb was detonated soon after in a controlled explosion by police sappers, and two more found in the area in time to neutralize them.

The attack killed 8-year-old Martin Richard, and 29-year-old Krystal Campbell woman and a Chinese graduate student at Boston University whose family requested her identity not be released. Another 176 people were wounded, including 17 who were listed in critical condition.