BOSTON — In what could be a major break in the Boston Marathon case, investigators are on the hunt for a man seen in a department-store surveillance video dropping off a bag at the site of the bombings, a Boston politician said Wednesday.
The development — less than 48 hours after the attack that left three people dead and more than 170 wounded — marked a possible turning point in a case that has investigators analyzing photos and videos frame by frame for clues to who carried out the twin bombings and why.
City Council president Stephen Murphy, who said he was briefed by Boston police, said investigators saw the image on surveillance video from a department store near the finish line, and matched the findings with witness descriptions of someone leaving the scene.
"I know it's very active and very fluid right now — that they are on the chase," Murphy told the Associated Press. He added: "They may be on the verge of arresting someone, and that's good."
The bombs were crudely fashioned from ordinary kitchen pressure cookers packed with explosives, nails and ball bearings, investigators and others close to the case said. Investigators suspect the devices were then hidden in black duffel bags and left on the ground.
As a result, they were looking for images of someone lugging a dark, heavy bag.
One department store video "has confirmed that a suspect is seen dropping a bag near the point of the second explosion and heading off," Murphy said.
The turn of events came with Boston in a state of high excitement over conflicting reports of a breakthrough.
A law enforcement official briefed on the investigation told the AP around midday that a suspect was in custody. But the FBI and the U.S. attorney's office in Boston said no arrests had been made.
By nightfall, there was no evidence anyone was in custody. No one was brought to court.
The John Joseph Moakley U.S. Courthouse was evacuated in the afternoon by officials calling out "code red," and bomb-sniffing dogs were sent inside.
The courthouse was swarming with scores of journalists, who were drawn there by the rumors that an arrest had been made in the case.
One of those evacuated, Dave Greenup, 58, who works at a restaurant inside the courthouse, said: "For the past couple days, I have been in a daze. All of a sudden, we get this evacuation thing. Every time we turn around now, there's something. I was really hoping they caught somebody. You want closure."
About 4:15 p.m., court employees were allowed back into the courthouse.
On Wednesday, investigators in white jumpsuits fanned out across the streets, rooftops and awnings around the blast site in search of clues. They picked through trash cans, plastic cup sleeves and discarded sports drink dispensers
Boston remained under a heavy security presence, and some people admitted they were nervous about being in public.
Tyler King, a personal trainer from Attleboro who works in Boston, said four of five clients canceled on him a day earlier because they were worried about venturing into the city. He took the train in, but "I kind of kept my head on a swivel."
Police were stationed on street corners across downtown Boston, while National Guardsmen set up tents on the Boston Common and stationed tactical vehicles.
Kenya Nadry, a website designer, took her 5-year-old nephew to a playground. "There's still some sense of fear, but I feel like Boston's resilient," she said. "The fine men in blue will take care of a lot of it."
Information from the New York Times was used in this report.