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.