Obama says suspect's capture closes 'important chapter' in Boston tragedy

President Obama lauded law enforcement for their work in bringing down the two known Boston bombing suspects, saying the dramatic capture of the lone survivor late Friday “closed an important chapter in this tragedy” – while pledging to get “answers” on what led to the attack.

“All in all this has been a tough week, but we have seen the character of our country once more,” the president said from the White House briefing room.

The president was already facing pressure from some members of Congress to hold the suspect, Dzhokhar Tsarnaev, as an enemy combatant. The president did not address these concerns in his remarks.

Obama kept his comments brief, leaving it to law enforcement to explain to the public the murky and confusing chain of events that kept Boston on edge – and in some cases on lockdown – up until Friday evening. Obama said the nation is “in debt” to police at all levels, who he said responded with “professionalism and bravery over five long days.”

As the suspect is treated and brought into custody, Obama acknowledged investigators still have much work to do and said the victims “deserve answers.” Three people died and dozens were injured in the Boston Marathon bombing Monday.

“We will determine what happened. We will investigate any association that these terrorists may have had,” Obama said.

Obama spoke after the weeklong hunt for the attackers ended with one suspect killed by police and another brought into custody late Friday.

The harrowing search for the surviving suspect lasted the entire day Friday, as law enforcement locked down several neighborhoods in the Boston suburbs – acting on a flurry of tips and going house to house looking for Tsarnaev.

Onlookers broke out in applause after the suspect was taken away in an ambulance, following a tense police standoff. His older brother, Tamerlan Tsarnaev, was killed during a chaotic chase and confrontation overnight after they allegedly killed a Massachusetts Institute of Technology police officer and carjacked an SUV.

The surviving brother is said to be injured and is being treated at a local hospital. Authorities will now ramp up the effort to determine whether the brothers were part of a broader plot and whether either or both of them got overseas training. The radicalized Muslims are said to be ethnic Chechens from Dagestan, a Russian region that borders Chechnya.

Obama did not reveal much additional detail in his remarks. But lawmakers made clear that in the weeks ahead, they will have questions for the administration about what could have led to the attack and how such a deadly assault can be prevented in the future. Chechnya is known for containing a virulent element of Islamic radicalism, but to date the region – which for years has been fighting Russia for independence – has not been known to have an interest in exporting terror to America.

“While we have made it more difficult for terrorists to carry out attacks from overseas, the attack on the Boston Marathon is indicative of the shift in terrorists' tactics in recent years to inspire people who are living in the United States to strike,” Rep. Michael McCaul, R-Texas, chairman of the House Homeland Security Committee, said in a statement. “While several plots of this nature have been thwarted, this is the first to succeed.  … In the coming weeks the Homeland Security Committee will begin to ask how this happened, and how we can prevent it from happening again.”

Sen. Lindsey Graham, R-S.C., and Sen. John McCain, R-Ariz., both argued that the suspect should be held as an “enemy combatant” for intelligence gathering purposes. In a statement, they said “the last thing we should want is for him to remain silent.” They said he could be held as a combatant “not entitled to Miranda warnings.”

There are a host of unanswered questions about the suspects’ motivations and possible training.

Fox News has learned that the older brother traveled to Russia, including Chechnya, in early 2012 and returned in July. His suspected YouTube site, which included radical jihadi videos, was launched the following month.

The FBI also acknowledged that they were asked to look into the older brother by a foreign government two years ago over his possible extremist ties. The FBI said they fully “scrubbed” him and interviewed him but “did not find anything.”