Boston bomb suspect captured in pictures

BOSTON: US investigators found images of a suspect who may have planted the bombs that killed three people and maimed scores more at the Boston marathon, officials said Wednesday.

No arrest has been made. But images from a surveillance camera and still pictures could mark a breakthrough ahead of a visit to the city by US President Barack Obama and his wife Michelle in what was being billed as a mission of "healing."

Two days after two bombs tore through crowds on the marathon finish line, wounding 180 people, Boston remained on edge.

The federal courthouse and part of a hospital used for the victims were briefly evacuated, while conflicting reports of an arrest brought a stern rebuke from the Federal Bureau of Investigation.

But a law enforcement official told that "there is an image of a person, of a potential suspect." Investigators were working "to locate and identify that individual," the official added.

The Boston Globe said the images may have captured the suspect planting one of the two bombs. Separate media reports indicated there were pictures of the suspect running away while other people slumped to the ground during the blast.

With no claim of responsibility made for the attack, the FBI said it has launched a "worldwide" hunt.

Massachusetts Governor Deval Patrick appealed for patience over the pace of the investigation.

"They are making progress. But it's going to take time," Patrick said on CNN. "Every hour, we're closer."

The FBI released photographs of the mangled metal remnants of a pressure cooker believed to have been used for one of the bombs, which sprayed nails, ball bearings and metal pellets into the crowds.

The lid of one pressure cooker was found on the roof of a nearby hotel.

Doctors at hospitals where the injured were taken say ball bearings and nails taken from patients were being used in the investigation.