April 17, 2013 -- Authorities have a clear picture of a potential suspect in the Boston Marathon bombings and are in the process of identifying that individual, sources told ABC News today.
ABC News' Boston affiliate WCVB reported surveillance video taken from cameras at Lord & Taylor along the marathon route were key to spotting the individual in question.
Other news organizations recently reported a suspect already had been taken into custody, but both the Boston Police Department and the FBI said no one has been arrested in connection with the bombing.
In the midst of the conflicting reporting, a federal courthouse in Boston was evacuated because of a bomb threat, a source with the U.S. Marshals told ABC News. As of this report, no suspicious devices have been found there.
Boston Marathon Bomb Made From Pressure Cooker
A pair of blasts erupted Monday afternoon near the finish line of the Boston Marathon, killing three people and injuring more than 170 others.
Authorities said they have been analyzing thousands of photos of the event and tracking down as many leads since the bombing. Tuesday ABC News reported part of a pressure cooker bomb had been recovered from the scene with wires, shrapnel and a circuit board. A Fagor brand pressure cooker like the one used in the attack can be bought from major retail outlets for around $140. Investigators said there was not enough evidence to determine if the second bomb was also made from a pressure cooker.
The evidence has been sent to FBI's lab in Quantico, Virginia, where law enforcement sources said the parts could provide a break in the case.
Investigators will use every clue, from the pressure cooker's manufacturer and retailers to the types of nails used in the shrapnel, to try and find out from where the bomb parts were purchased and by whom, the sources said.
Richard Clarke, former White House counter-terrorism advisor and now ABC News consultant, said that while pressure cooker IEDs have been found in Afghanistan and Pakistan, that doesn't necessarily point to foreign involvement, as the pots are so widely available and instructions for how to build the bombs are easily accessed online by anyone.
"It doesn't tell you much about who did it... But it does give you a lead perhaps of where it came from," Clarke said. "They [investigators] may be able to trace back a pressure cooker."
Along with tracking down the origin of the bomb parts, authorities are painstakingly going through hundreds of pictures and videos from the site of the bombing, hoping, as Clarke put it, to "stitch" together a picture of what exactly happened. It was possibly during this process that authorities identified the potential suspect spotted today.
Despite more than 48 hours passing without a suspect named, Clarke said he's confident the authorities will get their man.
"It may take a while, but this will be solved," he said.