Authorities closing in on marathon terrorist suspect?

Updated 3:40 p.m. April 17

Both CNN and the Boston Globe on Wednesday, April 17 reported that a suspect has been identified in the Boston Marathon terrorist bombing and that an arrest has been made or is imminent. Both backed off of that assertion about an hour later, and the Boston Police made a statement saying that no arrest had been made.

From the Globe:
“ …authorities have an image of a suspect carrying, and perhaps dropping, a black bag at the second bombing scene on Boylston Street, outside of the Forum restaurant.
Investigators are “very close” in the investigation, said the official, who declined to be named.That official said authorities may publicize their finding as early as this afternoon.The same official also said a surveillance camera at Lord & Taylor, located directly across the street, has provided clear video of the area, though it was unclear whether the image of the suspect was taken from that camera.  “The camera from Lord & Taylor is the best source of video so far,” said Dot Joyce, a spokeswoman for Boston Mayor Thomas M. Menino. “All I know is that they are making progress.”

Most experts hope that crucial information will be gleaned from video—footage from city surveillance systems, local businesses and videos from the smartphones of those watching the marathon.

This morning the LA Times reported that analysts from the FBI are “sifting through more than 10 terabytes of data for clues about who might have placed the bombs near the finish line. The data include call logs collected by cellphone towers along the marathon route and surveillance footage collected by city cameras, local businesses, gas stations, media outlets and spectators who volunteered to provide their videos and snap shots, said the federal law enforcement source.
The FBI has flown analysts from field offices across the country to Boston to watch and log hundreds of hours of video, he said.

I asked Amit Gavish, GM, Americas, BriefCam, via email, what he thought the prospects were for finding clues in the various video footage taken in the area of the finish line. In addition to working for Briefcam, a manufacturer of video synopsis systems which enable the very quick review of hours of video [],
Gavish, is a CPP, with 16 years of security and military experience in the U.S. and Israel. He served as the Deputy Director of Security at the Office of the President of the State Israel and was in charge of physical and information security. Before joining BriefCam, Gavish was a risk management consultant specializing in risk assessment, development of emergency plans and training programs.

Gavish said it will be important to look at video footage taken days before the marathon: “In my opinion, the person was there before. The person who did this most likely did some dry runs before the event, even days before and probably was there hours before the event.”

He said the footage from Monday is likely “crowded to the point where you can't see who put the device at the scene, and you have to go back a few days prior and see who was there … who looked suspicious, who was just walking by or loitering.”

He said there “are hundreds of cameras that could potentially have something. There are good cameras there—Boston PD, public cameras, stores in the neighborhood—but part of the effectiveness of the investigation is how fast you can get to something that you can work on,” he said.

I also did an email interview with Zvika Ashani, CTO of Agent Video Intelligence (Agent Vi). I asked Ashani how a product like Agent Video's VI-Search would  examine video from multiple sources.

Vi-Search can be “used in an offline mode on cameras that are not part of a large pre-installed surveillance system. For example, video can be retrieved from a store or a gas station, which is in the vicinity of the event. This video can then be quickly processed by the software (at a rate of about 10x) and then searched using the same query structure.”