Boston — With the second suspect in the Boston Marathon bombings captured alive, the nation waits for answers as to why all of this took place.

Federal law enforcement officials are pouring over evidence, and looking into the backgrounds of the two suspected bombers.

According to the Los Angeles Times, federal terrorism charges could soon be filed against 19-year-old Dzhokhar Tsarnaev, even as he remains hospitalized.

Tsarnaev and his older brother, 26-year-old Tamerlan Tsarnaev, are accused of setting off bombs at the marathon Monday, killing three people and leaving more than 170 wounded.

The Tsarnaevs arrived in the United States in 2002 after their ethnic Chechen family fled the troubled Caucasus region of southern Russia.

Chechnya is a predominantly Muslim area that has fought for full independence from Russia in the past.

On Thursday night, the brothers allegedly killed a Massachusetts Institute of Technology police officer before the older brother died in a shootout with police.

Dzhokhar Tsarnaev was captured alive Friday night after he was found hiding in a boat in a Watertown, Massachusetts, backyard.

He remained hospitalized Saturday afternoon at Beth Israel Deaconess Medical Center in Boston, where his brother was pronounced dead and where dozens of injured spectators were taken Monday after two bombs exploded at the finish line of the Boston Marathon.

The older brother traveled to Russia for six months in 2012 and law enforcement officials are now scrutinizing that trip to see if he met with extremists or received terrorism training.

In his weekly address Saturday morning, President Obama applauded the “heroism and kindness” on display in the aftermath of the bombings.

“Americans refuse to be terrorized,” Mr. Obama said. “Ultimately, that’s what we’ll remember from this week.”