Boston Marathon bombing: Conflicting reports about arrest

BOSTON - While CNN initially reported that Boston authorities had arrested a suspect in the marathon bombings, the Justice Department is saying no arrest has been made. The FBI is expected to hold a news conference at 3 p.m. MT Wednesday.

The news comes just 46 hours after two bombs exploded near the finish line of the Boston Marathon killing three people and injuring more than 170 others.

CNN's John King said the breakthrough in the case came from analysis of video from a department store near the site of the second explosion. Video from a Boston television station also contributed to the progress, said the source, who declined to be more specific but called it a significant development.

Authorities investigating the deadly bombings at the Boston Marathon 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.

A law enforcement official briefed on the investigation confirmed to The Associated Press on Wednesday that authorities 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.

FBI special agent in charge Richard DesLauriers said Tuesday that pieces of black nylon and fragments of the metal shrapnel were found in the area. Because of the fabric, DesLauriers said investigators believe the bombs were placed in a dark-colored backpack or bag.

The law enforcement representatives have been asking for any video, audio and photos taken by marathon spectators, even images that people think might not be significant."There has to be hundreds, if not thousands, of photos and videos" that might help investigators, state police Col. Timothy Alben said.

Investigators have gathered a large number of surveillance tapes from businesses and intend to go through them frame by frame.

The bomber may have been seen amid revelers, carrying an unusually heavy nylon bag, weighed down with shrapnel-packed explosives.

Similar pressure-cooker explosives have been used in Afghanistan, India, Nepal and Pakistan, according to a July 2010 intelligence report by the FBI and Homeland Security. Also, one of the three devices used in the May 2010 Times Square attempted bombing was a pressure cooker, the report said.

"Placed carefully, such devices provide little or no indication of an impending attack," the report said.

The Boston Marathon is one of the world's oldest and most prestigious races and about 23,000 runners participated. The attack may have been timed for maximum bloodshed: The four-hour mark is typically a crowded time near the finish line because of the slow-but-steady recreational runners completing the race and because of all the friends and relatives clustered around to cheer them on.

According to the race's website, 521 Colorado residents were registered to race Monday.