Boston suspect captured - but only by surveillance camera

THE BOSTON Marathon bomber has been caught . . . on film.

Law-enforcement authorities revealed Wednesday that they are "very close" - as a source told the Boston Globe - to a major break in the case of the worst domestic bombing attack since 9/11 after surveillance video captured footage of a suspect carrying and possibly dropping a black bag at the scene of the second of two explosions.

A spokeswoman for Boston Mayor Thomas Menino told the newspaper that "the best source of video" has proved to be a Lord & Taylor department store that faces out toward the sidewalk where one of the bombs - which killed three spectators at the iconic race on Monday and injured more than 170 others - went off.

That recorded video was one of many pieces of film - footage taken not just from store or street surveillance cameras but also spectator videos and TV news cameras recording some of the 23,000 runners crossing the finish line - that seem to be helping agents heat up a trail that might have otherwise grown cold, some 48 hours after the stunning attack.

Although the initial shock of the twin blasts faded, Americans still closely followed the hunt for the killers as well as new information released Wednesday about the third fatal victim to be identified. She was a 23-year-old Boston University graduate student and Chinese national named Lu Lingzi, who called herself by the Americanized name "Dorothy."

Boston University confirmed Wednesday that Lu was studying mathematics and statistics at the school and was due to receive her graduate degree in 2015. It said she and two friends had been watching the Boston Marathon near the finish line. One of the friends, also a BU student, was injured, while the other was unharmed, the university said.

"I saw her grow up, and a few scenes from the past are flashing through my mind. Now, she's becoming a girl, a bit Westernized, but a loud bang has changed everything," a former neighbor in Shenyang, Zhang Xinbo, wrote in a blog. "I think of her loved ones, and I don't know how they are coping with this painful news, while still searching for any thread of hope."

If the day was tinged by more sadness, it was also marred by much confusion. That was especially true for about an hour in the afternoon, when CNN, the Associated Press and a couple of other outlets reported that either an arrest had been made in the case or that one was imminent. Other major media such as NBC News insisted there'd been no such breakthrough, and soon the FBI weighed in, urging caution and noting that bad information could compromise the investigation.

That wasn't the only chaos. At roughly the same time as the bogus news reports, the federal courthouse in downtown Boston was evacuated - not because a suspect was en route, as some speculated, but because of a bomb threat.

Despite the bogus arrest reports, there was optimism that the mystery will be solved.

Boston City Council President Stephen Murphy said police have matched information from the surveillance footage with witness descriptions of someone leaving the scene.

There was one other bizarre twist in the Boston probe Wednesday. As the National Rifle Association was celebrating its defeat in the Senate of more widespread background checks for gun purchases, MSNBC was reporting that the gun lobby is also to blame for a law that is thwarting investigators at the marathon site.

It said a push for chemical "taggants" on gunpowder - which could tell where the explosive powder used on Monday was purchased - had been thwarted by the gun lobby.