THOUSANDS of law enforcement agents from around the United States were to attend a memorial today for a university police officer who authorities say was shot dead by the Boston Marathon bombing suspects.
US Vice President Joe Biden was to speak at the ceremony.
The service at the Massachusetts Institute of Technology honors 26-year-old Sean Collier, who police say was killed by bombing suspects Tamerlan and Dzhokhar Tsarnaev on campus on Thursday night. Tamerlan, 26, was killed in a separate shootout with police and Dzhokhar, 19, was captured and criminally charged.
U.S. officials say the ethnic Chechen brothers planted and detonated two pressure-cooker bombs near the finish line of the Boston Marathon on April 15, killing three people and injuring 264. Ten people lost limbs in the bombing.
Authorities released videos and photos of the suspects, still unidentified at the time, on Thursday. Hours later, Collier, who had worked at MIT since January 2012, was shot and killed.
Several major roads around the MIT campus, located across the Charles River from Boston, were closed in anticipation of Biden's arrival. But Boylston Street, a major downtown Boston artery and scene of the marathon finish line bombing, reopened to traffic and pedestrians on Wednesday morning.
MIT canceled Wednesday's classes in Collier's honor.
Collier, as well as the youngest victim of the bombing attack, 8-year-old Martin Richard, were buried in private ceremonies on Tuesday. It is not yet clear where or when Tamerlan Tsarnaev will be buried.
Officials at the Cambridge mosque where he sometimes worshipped, and was known to have twice disrupted services, said on Tuesday they were unsure if they would offer burial services if asked by the family.
Top U.S. security authorities faced a grilling yesterday about the handling of the investigation by lawmakers seeking answers to why Tamerlan Tsarnaev, flagged as a possible Islamist radical, was not tracked more closely.
His name was listed on the U.S. government's highly classified central database of people it views as potential terrorists, sources close to the bombing investigation said. The list is vast, including about 500,000 people, which means that not everyone on the list is closely monitored.
Tamerlan's younger brother lies wounded in a Boston hospital formally charged with using a weapon of mass destruction.
He is being represented by Miriam Conrad, the Boston area's top public defender, who has handled prior cases involving men accused of plotting to fly an explosive-laden remote-controlled plane into the Pentagon and helping to finance a 2010 planned car bomb attack in New York's Times Square.
Investigators have focused on a trip to Dagestan last year by the older Tsarnaev and whether he became involved with or was influenced by Chechen separatists or Islamist extremists there.
Russian authorities flagged him as a possible Islamist extremist in 2011. The FBI interviewed him in Massachusetts but found no serious reason for alarm.
Tamerlan Tsarnaev in February bought two large packages of fireworks from a New Hampshire store, a vice president at the company that runs the store said, though those packages would not have contained enough explosives to build the bombs used in the Boston attack.
QUESTIONS ABOUT FLOW OF INFORMATION
Senators said after Tuesday's briefing by FBI Deputy Director Sean Joyce and other officials that there may have been a breakdown in communication that kept authorities from tracking his apparent radicalization.
Senator Saxby Chambliss of Georgia, the ranking Republican on the Senate intelligence committee, said the briefing raised questions about the flow of information among law enforcement and intelligence agencies.
"I think there has been some stonewalls, and some stovepipes reconstructed, that were probably unintentional, but we've got to review that issue again, and make sure there is the free flow of information," he said.
The widow of Tamerlan Tsarnaev is assisting authorities and in absolute shock that her husband and brother-in-law were accused of the deadly blasts, her lawyer said.
Dzhokhar Tsarnaev's condition improved to "fair" from "serious" on Tuesday as he recovered from gunshot wounds at Beth Israel Deaconess Medical Center, where in an impromptu hearing on Monday he was charged with two crimes that could result in the death penalty if he were convicted.
Recovering enough to communicate by nodding his head and writing, the younger Tsarnaev has told authorities he and his brother acted alone, learned to build the bombs on the Internet and were motivated by a desire to defend Islam because of "the U.S. wars in Iraq and Afghanistan," NBC News reported.
NBC cited an unnamed U.S. counterterrorism source. Reuters could not confirm the information.