(Most recent update: 12:20 p.m. ET.)
People in Boston and across Massachusetts will pause for a moment of silence at 2:50 p.m. ET Monday — marking the time exactly one week ago when the first of two bombs exploded near the finish line of the Boston Marathon, killing three people and injuring more than 170.
Meanwhile, the surviving suspect in the bombings remains in serious condition at Boston's Beth Israel Deaconess Hospital. As NPR's David Schaper reported on Morning Edition, it's not clear yet how or when 19-year-old Dzhokhar Tsarnaev was wounded or who inflicted some of his injuries. It's possible he tried to kill himself. Sources familiar with the investigation into the bombings have told NPR that wounds to his neck and jaw area are preventing Tsarnaev from talking. But, they say, he has communicated in writing.
David added that federal prosecutors are preparing criminal and possible terrorism-related charges against Tsarnaev, and there is word of more video evidence: Massachusetts Democratic Gov. Deval Patrick told NBC-TV on Sunday that surveillance video shows the suspect putting down a backpack and not reacting at all when the first bomb went off.
Patrick called the images "chilling."
NPR's Dina Temple-Raston told Morning Edition that some of the video evidence, investigators say, shows Dzhokhar slipping a backpack off his shoulder, placing it on the ground, making a phone call and walking away. The second of the two explosions, she said, appeared to happen "right where that backpack had been."
Tamerlan Tsarnaev, Dzhokhar's 26-year-old brother and the other suspect in the bombings, died after a gun battle with police early Friday in the Boston suburb of Watertown, Mass. The brothers allegedly killed an MIT campus police officer and seriously wounded a Boston transit police officer during a wild shooting spree that began Thursday night and lasted into the early hours of Friday.
Dzhokhar Tsarnaev was captured Friday evening after a harrowing day when much of the Boston area was locked down during the police manhunt. He was discovered in a boat stored in a Watertown family's backyard. Authorities are anxious to know whether anyone else may have been involved and whether any more attacks were planned.
Investigators also are trying to piece together how Tamerlan Tsarnaev may have been radicalized in recent years, NPR's Temple-Raston added Monday. They're looking to interview his wife. The Tsarnaev brothers, both Muslims, came from an ethnic Chechen family that had been living in the U.S. for about a decade. Tamerlan was a legal resident, and Dzhokhar became a U.S. citizen last year.
We'll keep an eye on developments as the day continues and update this post with the news.
Update at 12:20 p.m. ET. Tamerlan Tsarnaev's "Closest American Friend" And Two Other Young Men Were Murdered Three Years Ago; Case Remains Unsolved:
After a Buzzfeed report that "associates of slain Boston Marathon bombing suspect Tamerlan Tsarnaev now believe he may have been involved in a 2011 triple murder that claimed the life of his closest American friend, Brendan Mess," the prosecutor's office in Middlesex County, Mass., is going to go back to see if there's any connection between Tsarnaev and that unsolved crime, Reuters reports.
The wire service writes:
" 'We are definitely going to pursue any new leads,' said Stephanie Guyotte, a spokeswoman for the Middlesex District Attorney's office. She said it was fair to say that investigators will check to see if Tsarnaev had anything to do with the crime."
John Allan, owner of Wai Kru Mixed Martial Arts in Allston, Mass., where Tsarnaev once boxed, had earlier told the Boston Globe that the 26-year-old had once introduced Mess as his best friend. Then two years ago, the Globe wrote, "Mess and two other men were brutally killed in a Waltham apartment where they were found by police with their throats slit and their bodies covered with marijuana. The murders remain unsolved."
According to Buzzfeed, a mutual friend says Tsarnaev did not come to Mess' funeral. "A few months after Mess's murder," Buzzfeed adds, "Tsarnaev went to Russia for six months."
Guyotte, the prosecutor's spokeswoman, has also told the local Waltham Patch that the triple murders are "an active homicide case and that investigators would pursue any new leads they receive."
While friends are asking whether Tsarnaev might have been involved in the murders, The Wall Street Journal notes that the killings came at a tumultuous time in Tsarnaev's life and raises the prospect that they might have been among the reasons he appears to have turned to a radical form of Islam.
Update at 11:30 a.m. ET. Funeral For Krystle Campbell:
The funeral for 29-year-old Krystle Campbell, one of the three people killed in the bombings, is being held this hour in her hometown of Medford, Mass. The Boston Globe says "some 200 members of Teamsters Local 25 members began gathering at St. Joseph's Church before 8 a.m. today, promising to block protesters from the Westboro Baptist Church if they follow through on a threat to picket the funeral."
A memorial service for 23-year-old Lingzi Lu of China, who was a graduate student at Boston University, is planned for 7 p.m. ET Monday at the school. The third person killed at the marathon was 8-year-old Martin Richard of Dorchester, Mass. He was remembered during a Mass on Sunday at Dorchester's St. Ann Parish. Sean Collier, the 26-year-old slain MIT police officer, is to be remembered later this week.
Update at 10:45 a.m. ET. President Obama Will Observe Moment:
President Obama will also "observe a moment of silence in honor of the victims of the Boston Marathon bombings" at 2:50 p.m. ET, the White House says in a statement sent to reporters. He will do so in private, the statement adds.
Update at 10 a.m. ET. Wounded Officer "Shows Hopeful Signs":
"The transit police officer critically wounded in a gunbattle with the marathon bombing suspects opened his eyes, wiggled his toes and squeezed his wife's hand yesterday for the first time since he nearly bled to death Friday — hopeful signs for his doctors and family," The Boston Herald writes. "Three-year veteran MBTA cop Richard Donohue remains in critical but stable condition at the surgical intensive care unit at Mount Auburn Hospital."
Update at 8:50 a.m. ET. Dzhokhar Tsarnaev Remains In Serious Condition.
The U.S. Attorney's office in Massachusetts tweets that:
"According to BIDMC marathon bombing suspect remains in serious condition this morning. Releasing info at hospital's request."
BIDMC is Beth Israel Deaconess Medical Center.
As Monday dawned, here were some of the related headlines:
-- "Turn To Religion Split Bomb Suspects' Home." (The Wall Street Journal, behind a paywall)
-- "Dead Suspect Broke Angrily With Muslim Speakers." (The Boston Globe)
-- "Suspects Seemed Set For Attacks Beyond Boston." (The New York Times)
-- "The Inside Story" Of The Investigation. (CBS News' 60 Minutes)
-- "Should Marathon Bomber Be Treated As An Enemy Combatant?" (Morning Edition)
Note: As happens when stories such as this are developing, there will likely be reports that turn out to be mistaken. Wednesday, for example, there were reports from CNN, the AP, WBUR and others that authorities either had arrested a suspect or were about to do that. It turned out that no one had been arrested or taken into custody. We will focus on news being reported by NPR, other news outlets with expertise, and statements from authorities who are in a position to know what's going on. And if some of that information turns out to be wrong, we'll update.