Significant progress reported in Boston Marathon investigation

Investigators have found video of a man that they believe may have planted the deadly bombs at the Boston Marathon, a person briefed on the matter said this evening, saying that they had pinpointed the image on video that was captured shortly before the blast.

The possible break in the case came as investigators have pored over scores of videos and photographs that they solicited from surveillance cameras from nearby businesses, smartphones, and television crews who were there filming the Boston Marathon when the blasts went off on Monday near the finish line.

The revelation of the video was the first sign that the authorities might be moving closer to discovering who was behind the attacks, which killed three people and injured more than 170.

No arrests have been made, and the suspect in the video hasnot been identified by name, US government officials said. Nerves were jolted further by an inaccurate report on cable news network CNN earlier that a bombing suspect had been arrested.

As the Boston investigation went into a third day, the US remained on high alert. New York City officials said there had been an increase in reports of suspicious packages. In Oklahoma City, City Hall was briefly evacuated this morning as authorities examined a stolen rental truck that was parked outside, just a few days short of the anniversary of the 1995 bombing of the nearby Alfred P Murrah Federal Building.

In Washington, parts of two Senate office buildings were closed as officials investigated reports of suspicious letters or packages, and the Secret Service said that a letter addressed to president Barack Obama, containing a suspicious substance, had been intercepted at a screening facility outside the White House.

And in Boston, the John Joseph Moakley US 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 from around the world, who had been brought there by rumors - reported early today afternoon by several news organizations but forcefully denied by the FBI and the Boston Police Department - 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."

In New York City, the Police Department has received 143 reports of suspicious packages from just after the Boston explosions, an increase of more than 300 per cent over a similar time period last year, the police commissioner, Raymond W Kelly, said.

The previously unidentified victim of Monday's blast was described today as a young woman whose ambitions and hard work took her from her rust-belt hometown in northeast China to graduate studies at Boston University. The woman was identified as Lu Lingzi by a classmate, a Chinese university official and a state-run newspaper in her home city.

Ms Lu (23) had moved to Boston to study statistics at Boston University after studying international trade at the Beijing Institute of Technology, according to a resume that was posted online. In her hometown, Shenyang, The Shenyang Evening News, the state-run newspaper that announced her death, darkened its website in honour of a "Shenyanger who passed away in a far-away place."

The three people killed in the blasts were a cross-section of Boston, brought together seemingly at random to watch one of the city's proud traditions: the marathon. There was Lu, one of the thousands of international students drawn to the area's universities.

There was Martin Richard, a vivacious 8-year-old third-grader from a well-loved family in Dorchester, a tight-knit community. And there was Krystle Campbell (29) of Arlington, Mass., a hard-working woman known for her sense of humor who had started working at restaurants as a waitress in high school and now worked as a restaurant manager.

A 5-year-old boy remains in critical condition at Boston Medical Center, Dr. Peter Burke, the chief of trauma services at the hospital said at a morning briefing. He was one of 19 patients who remain there, he said, and one of two who were in critical condition - down from 10 who were in critical condition today.

"I'm very optimistic," Dr Burke said, adding that it was possible that another patient or two could be discharged today. "I will not be happy until they're all home," he said. Three children who were injured in the blast remained at Boston Children's Hospital, the hospital announced: a 2-year-old boy with a head injury was listed in good condition, while a 10-year-old boy and a 9-year-old girl, both with leg injuries, were in critical condition.

A piece of the lid of one of the pressure cookers that investigators believe were used as explosive devices in the bombings was found on a rooftop near the blast - giving a sense of the tremendous force of the explosion.

Yesterday, law enforcement officials said the bombs were most likely rudimentary devices made from ordinary kitchen pressure cookers, except they were rigged to shoot sharp bits of shrapnel into anyone within reach of their blast and maim them severely.

The pressure cookers were filled with nails, ball bearings and black powder, and the devices were triggered by "kitchen-type" egg timers, one official said.

NYT