Official Spells Out Specific Red Flags That Could Help Authorities Find Attackers

BOSTON (CBSNewYork) — The hunt for a suspect in the Boston Marathon bombings began minutes after Monday’s attacks.

On Tuesday afternoon, FBI officials held a news conference stating that it had received more than 2,000 tips as of noon. Many of them have been viewed, analyzed and vetted, according to authorities.

Richard DesLauriers, Special Agent in Charge of the FBI’s Boston Division, said “someone knows who did this.”

MORE: Full Coverage from CBS Boston | PHOTOS: From The Scene | Aftermath Of Boston Bombings | Security Beefed Up Around The Globe

DesLauriers asked business owners to review and preserve any surveillance video they may have in its original form. He also issued a request of the general public to speak out if they have any information regarding the following:

* If they know of an individual who expressed a desire to target the marathon.

* Someone who showed suspicious interest in creating explosive devices.

* Heard noise of explosions in a remote area that may have been done as a test.

* Someone who may have been carrying dark, heavy bags, in vicinity of the blasts.

“The investigation is in its infancy,” DesLauriers said. “We’re working hard to get the answers.”

The FBI has also recovered forensic evidence revealing the bombs were packed with nails and ball bearings. Investigators believe the devices were placed in pressure cookers and then carried to the scene in nylon backpacks.

Steven Rogers, a retired naval intelligence officer with the FBI’s Joint Terrorism Task Force, said authorities look at bomb fragments at the scene and compare them to other attacks.

“They are going to try and find a signature to that bomb and if that bomb is similar to a bomb that was used in another city somewhere in the world…that’s how you get these leads,” Rogers said.

And video shot by the public and news crews are all being carefully examined, officials said.

When synagogues were fire bombed in Bergen County, N.J., the prosecutor’s office canvassed stores to see if anyone had bought materials to make Molotov cocktails.

That investigation led to a surveillance videotape of the suspect at a Walmart.

“In this case, there were receipts. Law enforcement people got and traced numbers of those receipts back to a computers that led to the arrests of those suspects in the synagogue bombings,” Rogers said.

Rogers believes the bombs were more than likely placed at the Boston Marathon locations after dogs had swept the area.

The key to the investigation will be the public and if anyone saw anything suspicious — not only on the day of the attacks, but even days in advance.

Experts on terrorism said people who set off bombs usually case the areas they target beforehand.

Rogers said it is also possible dogs were not able to pick up a scent because of the type of chemical in the bombs.

Share your thoughts in the comments section below…