BOSTON - From Boston and Washington to Russia, investigators pressed for answers Wednesday about the Muslim radicalism believed behind the Boston Marathon bombing while more than 4,000 mourners paid tribute to an MIT police officer who authorities say was gunned down by the bombers.
Among the speakers at the memorial service in Cambridge was Vice President Joe Biden, who condemned the bombing suspects as "two twisted, perverted, cowardly, knockoff jihadis."
Dzhokhar Tsarnaev, 19, was listed in fair condition as he recovered from wounds suffered during a getaway attempt. He could get the death penalty if convicted of plotting with his older brother, now dead, to set off the pressure-cooker bombs that killed three people and wounded more than 260 on April 15. Tamerlan Tsarnaev, 26, died in a shootout with police.
The bombs were detonated by remote control, according to U.S. officials close to the investigation who spoke on condition of anonymity. It was not clear what the detonation device was, but the charges against Dzhokhar say he was using a cellphone moments before the blasts.
U.S. officials also said Dzhokhar has told interrogators he and his brother were angry about the U.S. wars in Muslim Afghanistan and Iraq.
In Russia, U.S. investigators traveled to the predominantly Muslim province of Dagestan and were in contact with the brothers' parents, hoping to gain more information.
The parents, Anzor Tsarnaev and Zubeidat Tsarnaeva, plan to fly to the U.S. today, the father was quoted as telling the Russian state news agency RIA Novosti. The family has said it wants to bring Tamerlan's body back to Russia.
At the Massachusetts Institute of Technology, bagpipes wailed as students, faculty and staff members and throngs of law enforcement officials paid their respects to MIT police officer Sean Collier, who was ambushed in his cruiser three days after the bombing.
The line of mourners stretched for a half-mile. They had to make their way through tight security, including metal detectors and bomb-sniffing dogs.