Investigators are preparing to arrest a suspect in relation to Monday's Boston marathon bombings, officials have told US media.
The breakthrough reportedly came from security video of a man dropping off a bag on the street near the race's finish line, before walking away.
The twin blasts killed an eight-year-old boy, a woman aged 29 and a postgraduate student from China.
Officials are due to hold a press conference at 17:00 ET (21:00 GMT).
Investigators have been sifting through thousands of pieces of evidence, ranging from video recorded on mobile phones to fragments of shrapnel removed from the victims' legs. More than 170 people were wounded in the attack.
The image of the suspect came from surveillance video recorded at a department store across the street from the site of the second blast, CNN reported.
The breakthrough reportedly came from security video of a man dropping off a bag on the street near the race's finish line, before walking away.
The twin blasts killed an eight-year-old boy, a woman aged 29 and a postgraduate student from China.
Officials are due to hold a press conference at 17:00 ET (21:00 GMT).
Investigators have been sifting through thousands of pieces of evidence, ranging from video recorded on mobile phones to fragments of shrapnel removed from the victims' legs. More than 170 people were wounded in the attack.
The image of the suspect came from surveillance video recorded at a department store across the street from the site of the second blast, CNN reported.
