Photos: Evidence Gathered From Marathon Crime Scene

April 17, 2013

Authorities investigating the deadly bombings at the Boston Marathon have recovered a piece of circuit board that they believe was part of one of the explosive devices, and also found the lid of a pressure cooker that apparently was catapulted onto the roof of a nearby building, an official said Wednesday.

A law enforcement official briefed on the investigation confirmed to The Associated Press that authorities have recovered what they believe are some of the pieces of the explosive devices. The official spoke on condition of anonymity because this person was not authorized to publicly discuss evidence in the ongoing investigation.

A person close to the investigation previously told AP the bombs consisted of explosives put in 1.6-gallon pressure cookers, one with shards of metal and ball bearings, the other with nails.

Investigators in white jumpsuits fanned out across the streets, rooftops and awnings around the blast site in search of clues on Wednesday.

This image from a Federal Bureau of Investigation and Department of Homeland Security joint bulletin issued to law enforcement and obtained by The Associated Press, shows the remains of a pressure cooker that the FBI says was part of one of the bombs that exploded during the Boston Marathon. (FBI/AP)

Investigators look through the top of a building on Boylston Street on Wednesday, two days after two bombs exploded just before the Boston Marathon finish line. (Julio Cortez/AP)

Investigators comb through the scene of one of the blast sites of the Boston Marathon explosions Wednesday. (Julio Cortez/AP)

Two men in hazardous materials suits put numbers on the shattered glass and debris as they investigate the scene at the first bombing on Boylston Street on Tuesday. (Elise Amendola/AP)

A sign lies on the street as investigators comb through one of the Boston Marathon blast sites on Wednesday. (Julio Cortez/AP)

Investigators comb through Boylston Street just beyond the finish line of the Boston Marathon on Wednesday, two days after two bombs exploded.(Julio Cortez/AP)

This program aired on April 17, 2013. The audio for this program is not available.

Boston Marathon Bombings