RICHMOND, Va. (WTVR)--Two days after explosives killed three people and wounded more than 180 during the Boston Marathon, investigators have made possible breakthroughs in the case.

The FBI is reviewing surveillance video of a possible suspect taken from the Lord and Taylor Department store and video footage from a Boston T.V. station. Authorities want to question a man who was seen on the video wearing a white baseball cap, a light-colored hooded sweatshirt and a black jacket.

Several components of the bombs are also heading to the FBI’s crime lab in Quantico Virginia, where analysts will attempt to reconstruct the devices used in the attacks.

Former FBI profiler Greg McCrary says the lab, the most sophisticated in the country, will help investigators narrow their focus using forensic evidence.

McCrary recalls one of his cases a few years back where analysts were able to determine the suspect owned a Golden Retriever.

“They’ll look at everything, they’ll look at exactly how these things were constructed,” McCrary says. “The unexploded devices hold the potential for the greatest evidence.”

Federal authorities believe the suspect or suspects used a pressure cooker bomb in at least one of Monday’s explosions.

They say the simplicity of such a bomb can make it hard to trace to any particular group.

The recipe for a pressure cooker bomb can easily be found on the internet, which could indicate domestic terrorism. However, the bombs have also been used by international terrorists groups over the past few years.

The FBI has already cleared a Saudi National who was injured in the attacks. While there were rumors of an arrest of another suspect early Wednesday afternoon, those reports turned out to be false.

McCrary says in extremely high profile cases, the FBI is placed under considerable pressure to find those responsible and mistakes can easily be made in the process.

“The pressure is there to solve it and solve it quickly,” McCrary says. “The important thing is to solve it correctly.”