- Three of Dzhokhar Tsarnaev's friends are accused of covering for him after the attacks
- No burial plot made available for the body of Tamerlan Tsarnaev
- His body is undergoing a second autopsy at the request of relatives
The trail of clues after bombings that shattered the Boston Marathon last month has provided investigators with abundant information.
The younger of the two brothers police say carried out the attacks, Dzhokhar Tsarnaev, was initially talkative after his capture, providing authorities with crucial details.
Here's what we've learned recently:
The Boston Marathon was not the original target, Dzhokhar Tsarnaev told investigators. He and his brother, Tamerlan Tsarnaev, initially considered a suicide attack on Boston's massive Independence Day celebration, which draws about 500,000 people.
But the homemade bombs they built in Tamerlan's apartment, where he lived with his wife and child, were finished sooner than expected, the younger brother said, according to a U.S. law enforcement official briefed on the investigation.
They chose the race a day or two before its start.
Covering for friends
Three of Dzhokhar Tsarnaev's friends are accused of covering for him after the attacks.
Dias Kadyrbayev, Azamat Tazhayakov and Robel Phillipos went to his dorm room and removed a laptop and a backpack containing parts of fireworks, according to an affidavit filed in the case.
Kadyrbayev had seen pictures of the suspects released by the FBI and texted Dzhokhar Tsarnaev to tell him "he looked like the suspect on television." Tsarnaev texted back "lol" and added, "come to my room and take whatever you want."
Kadyrbayev and Tazhayakov face charges of conspiring to discard potentially incriminating articles, and Phillipos was charged with making false statements to investigators.
A lawyer for Kadyrbayev said his client turned over the laptop to police.
The three began attending the University of Massachusetts Dartmouth in 2011, along with Tsarnaev.
Kadyrbayev and Tazhayakov were already in federal custody on suspicion of violating the terms of their student visas when they were charged.
Wounded but alive
Dzhokhar Tsarnaev was drenched with blood and only partly conscious, when he arrived at Beth Israel Hospital after a standoff with police just over two weeks ago, a senior hospital official told CNN.
Days after his arrival, he opened up to investigators, officials have said, giving them valuable clues.
He has since been transferred to a prison hospital and has become less forthcoming since being read his Miranda rights. Tsarnaev's defense team now includes Judy Clarke, one of the nation's foremost experts on keeping clients off death row.
His condition has improved, and he is able to speak and interact with the staff, a prison spokesman said.
For nearly two weeks, Tamerlan Tsarnaev's body lay unclaimed at the Boston medical examiner's office.
An uncle living in the United States, who had publicly condemned the brothers, had a funeral home pick it up Thursday.
Ruslan Tsarni, who lives in Maryland, had called the alleged bombers "losers," after the marathon attacks.
After residents near the funeral home that received Tsarnaev's body protested, it was moved to a different one.
Now a quest is underway to find Tsarnaev a resting place in Massachusetts. But before, the body will undergo a second "independent" autopsy demanded by his relatives.
His parents in Dagestan decided not to fly the remains there for burial, said family spokeswoman Heda Saratova.
There is no gravesite yet for the 26-year-old, said Peter Stefan, the owner of the funeral home. If no cemetery is found after the second autopsy, he plans to ask the government to find a grave.
He read Tamerlan Tsarnaev 's death certificate to CNN over the phone Friday.
"Gunshot wounds of torso and extremities," Stefan said. "Blunt trauma to head and torso."
Authorities have said his younger brother may have run him over as they resisted arrest days after the marathon attacks.
Widow in hiding
Katherine Russell, Tamerlan Tsarnaev's widow, remained largely out of view this week inside her parents' home.
According to her attorney, Amato DeLuca, the 24-year-old widow knew nothing of plans to bomb the race, and reports of her husband's involvement came as an "absolute shock" to Russell and her family.
But two sources familiar with the investigation told CNN that she spoke to her husband after his picture appeared on national television as a suspect.
The nature of the conversation remains under investigation, but the sources said there was some concern that Russell spoke with her husband but did not call authorities who were still seeking to identify the men in the photos.
Times Square foible
Dzhokhar Tsarnaev has told investigators that he and his brother decided to try to bomb Times Square as they talked the night of April 18 in a Mercedes SUV they carjacked in Cambridge, Massachusetts.
They still had five pipe bombs and a "pressure-cooker bomb" left over.
But the plan dissolved, when the driver of the vehicle, whom they held hostage for 90 minutes, escaped and police were notified. The violent chase that cost Tamerlan Tsarnaev his life ensued.
The man, who CNN is describing only as Danny because of privacy and safety concerns, said there was a difference of personalities between the brothers.
Tamerlan Tsarnaev kept talking throughout the ordeal, barking out orders, detailing his hatred of Americans and asking Danny to remain calm.
"If you cooperate, I won't kill you," said Tamerlan Tsarnaev, according to Danny.
While the talkative Tamerlan took the lead during the carjacking, the quiet Dzhokhar responded to multiple orders, such as getting money from an ATM, he said.
Tsarni has claimed that a man known as "Misha" was responsible for radicalizing Tamerlan Tsarnaev. On Monday, a U.S. government official told CNN that FBI agents had interviewed Misha.
The man, whose real name is Mikhail Allakhverdov, denied ever encouraging a violent take on Islam and says he was not Tamerlan's teacher, according to a New York Review of Books writer who says he interviewed Misha.
Federal agents are also looking into possible links between Tamerlan Tsarnaev and a Canadian boxer-turned-jihadist killed by Russian troops in 2012, a source being briefed on the investigation said. William Plotnikov and six others died in a firefight with Russian forces in Dagestan in July 2012, while Tsarnaev was visiting the region, the source said.
Of the scores of people injured in the blasts, 12 remain in five Boston-area hospitals, though none is in critical condition, according to information the hospitals provided to CNN.
Bombing survivor Jarrod Clowery told a news conference how impressed he was by the first responders who helped him and so many others and how coordinated they were -- even better than the best drive by New England Patriots quarterback Tom Brady.
"No disrespect to Tom Brady, I love him, but he can't hold a candle to [those] people," he said.
One of the biggest questions remaining is whether federal intelligence officials could have done more to prevent the attacks.
Russian authorities twice alerted U.S. authorities that Tamerlan Tsarnaev and his mother, Zubeidat, may have become radical Islamists.
The two were entered into a terror related database in the United States.
"Based on what I can see so far, the FBI performed its duties. The Department of Homeland Security did what it was supposed to be doing," President Barack Obama said this week. "But this is hard stuff."
An independent review by the Intelligence Community inspector general is underway.