A Boston Marathon bombings suspect has been identified, investigation sources say.
Al Jazeera's Alan Fisher, reporting from Boston, said that there were conflicting reports as to whether the suspect had been arrested. However, police and the Homeland Security said the FBI did not have anyone in custody.
"I've been told ... that an arrest is coming," Fisher said.
US law enforcement sources said earlier investigators of the Boston Marathon bombings believed they had identified a suspect in the Boston marathon bombing from security video.
An official announcement on the issue is expected at 5pm (2100 GMT) on Wednesday.
US media reports said that a suspect had been identified in a surveillance video from a department store near the explosion.
Authorities have an image of a suspect carrying a black bag at the second bomb site, they added without providing further details about the suspect.
Investigators of the bombings searched thousands of pieces of evidence from cell phone pictures to shrapnel shards pulled from victims' legs.
Based on shards of metal, fabric, wires and a battery recovered at the scene, the focus turned to whoever may have made bombs in pressure cooker pots and taken them in heavy black nylon bags to the finish line of the world-famous race watched by crowds of spectators.
The blasts at the finish line of Monday's race injured 176 people and killed three: an 8-year old boy, Martin Richard, a 29-year-old woman, Krystle Campbell and a Boston University graduate student who was a Chinese citizen.
Boston University identified the student as Lu Lingzi.
No one has claimed responsibility for the attack.