BOSTON -- The Boston area held funerals for two more of its dead Friday -- including an 8-year-old boy -- as more details emerged from U.S. officials and family members about how the two Boston Marathon bombing suspects may have been swayed by a radical, anti-American strain of Islam.

Dzhokhar Tsarnaev's condition was upgraded from serious to fair as investigators continued building their case against the 19-year-old college student. He could face the death penalty after being charged Monday with joining forces with his brother, now dead, in setting off the shrapnel-packed pressure-cooker bombs that killed three people.

Martin Richard, a schoolboy from Boston's Dorchester neighborhood who was the youngest of those killed in the April 15 blasts at the marathon finish line, was laid to rest after a family-only funeral Mass.

"The outpouring of love and support over the last week has been tremendous," the family said in a statement. "This has been the most difficult week of our lives."

A funeral also was held for Massachusetts Institute of Technology police officer Sean Collier, 26, who authorities said was shot to death by the Tsarnaev brothers on April 18. A memorial service for Collier was scheduled for Wednesday at MIT, with Vice President Joe Biden expected to attend.

More than 260 people were injured by the bomb blasts. About 50 are still hospitalized.

Authorities believe neither brother had links to terror groups. However, two U.S. officials said on Tuesday that Tamerlan Tsarnaev, 26 -- who died last week in a gunbattle -- frequently looked at extremist websites, including Inspire magazine, an English-language online publication produced by al-Qaida's Yemen affiliate. The magazine has endorsed lone-wolf terror attacks.

Both officials spoke on condition of anonymity because they were not authorized to discuss the investigation publicly.

Family members reached in the U.S. and abroad by The Associated Press said Tamerlan was steered toward a strict strain of Islam under the influence of a Muslim convert known to the Tsarnaev family only as Misha.

After befriending Misha, Tamerlan gave up boxing, stopped studying music and began opposing the wars in Afghanistan and Iraq, according to family members, who said he turned to websites and literature claiming the CIA was behind 9/11.

"Somehow, he just took his brain," said Tamerlan's uncle, Ruslan Tsarni of Montgomery Village, Md., who recalled conversations with Tamerlan's worried father about Misha's influence.

"You could always hear his younger brother and sisters say, 'Tamerlan said this,' and 'Tamerlan said that.' Dzhokhar loved him. He would do whatever Tamerlan would say," recalled Elmirza Khozhugov, the ex-husband of Tamerlan's sister. He spoke by telephone from his home in Almaty, Kazakhstan.

The brothers, who came to the U.S. from Russia a decade ago, were raised in a home that followed Sunni Islam, the religion's largest sect, but were not regulars at the mosque and rarely discussed religion, Khozhugov said.

In 2008 or 2009, Tamerlan met Misha, a heavyset bald man with a reddish beard. Khozhugov didn't know where they met but believed they attended a Boston-area mosque together.

Hoping to learn more about the motives, U.S. investigators traveled to southern Russia on Tuesday to speak to the parents of the two suspects, a U.S. Embassy official said.

The parents live in Dagestan, a predominantly Muslim province in Russia's Caucasus, where Islamic militants have waged an insurgency against Russian security forces for years.

A lawyer for the family, Zaurbek Sadakhanov, said the parents had just seen pictures of the mutilated body of their elder son and were not up to speaking with anyone.

In Massachusetts, the state House turned aside a bid by several lawmakers to reinstate the death penalty in certain cases, including the murder of police officers. In a 119-38 vote, the House sent the proposal to a study committee rather than advance it to an up-or-down vote.