(Most recent update: 10:45 a.m. ET.)
As investigators learn more about the surviving suspect in the Boston Marathon bombings and what Dzhokhar Tsarnaev and his older brother, Tamerlan, allegedly did, the initial theory is that "these two young men were working on their own," NPR's Dina Temple-Raston said Tuesday on Morning Edition.
Authorities continue to question 19-year-old Dzhokhar Tsarnaev, who remains hospitalized in serious condition. He's being treated at a Boston hospital for a variety of injuries he sustained during gun battles with police on Friday. It's also possible he tried to kill himself before he was captured that evening in the Boston suburb of Watertown, Mass.
His 26-year-old brother died of injuries early Friday.
Investigators say they are hearing from Tsarnaev through notes he's writing in response to questions. Other than one comment from the magistrate who presided at his hospital-bed arraignment Monday, there's been no indication the suspect is able to speak more than a word or two at a time. The magistrate reported that Tsarnaev said "no" when asked if he could afford a lawyer.
According to law enforcement sources Dina has spoken with, the information they've gotten from the 19-year-old leads them to suspect — so far — that Tamerlan Tsarnaev was the "driving force" behind the bombings at the marathon (which killed three people and wounded more than 200).
The information Dzhokhar Tsarnaev has been giving to investigators, Dina added, has them theorizing the attack was "in a sense a homegrown plot with a little bit of an international flavor." Tamerlan Tsarnaev, who reportedly had grown increasingly interested in an extremist form of Islam in recent years, traveled to Russia at least once. The family has Chechen roots.
CNN says investigators also believe the brothers were influenced by things they read on the Internet, and may have learned about bomb-making there, as well.
An important reminder: The investigation is still in its early stages. Authorities will uncover much more evidence. The picture of what led the brothers to allegedly plant bombs at the marathon and then, allegedly, kill an MIT police officer and engage in a harrowing gun battle with authorities, could change substantially.
We'll be following Tuesday's developments and will update as news comes in.
Update at 10:45 a.m. ET. Friends Convinced That Triple Murder In 2011 Happened On Sept. 11:
We reported Monday that prosecutors in Middlesex County, Mass., plan to take another look at an unsolved triple murder from 2011 in which one of the victims was a friend of Tamerlan Tsarnaev. On Tuesday, the Boston Globe reported that even though the death certificates of the victims say they died on Sept. 12 that year, friends and relatives are convinced they were killed on Sept. 11 — the 10th anniversary of the worst terrorist attacks in the nation's history.
Earlier, these were some of the morning's related headlines:
-- If Convicted, Tsarnaev Could Face Death Penalty. (The Washington Post)
-- "Bedside Transcript Of Boston Bombing Suspect Hearing." (The Boston Globe)
-- "Officials Say They Had No Authority To Watch Older Suspect." (The New York Times, which limits the number of stories that can be read for free.)
Note: As happens when stories such as this are developing, there will likely be reports that turn out to be mistaken. 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.