BOSTON (AP) — Lawmakers are asking tough questions about how the government tracked suspected Boston Marathon bomber Tamerlan Tsarnaev when he traveled to Russia last year, renewing criticism from after the Sept. 11 attacks that failure to share intelligence may have contributed to last week's deadly assault.

Following a closed-door briefing on Capitol Hill with the FBI and other law enforcement officials on Tuesday, Sen. Saxby Chambliss, R-Ga., vice chairman of the Senate Intelligence Committee, said it doesn't appear yet that anyone "dropped the ball." But he said he was asking all the federal agencies for more information about who knew what about the suspect.

"There still seem to be serious problems with sharing information, including critical investigative information ... not only among agencies but also within the same agency in one case," said committee member Sen. Susan Collins, R-Maine.

Lawmakers intensified their scrutiny as funerals were held Tuesday for an 8-year-old boy killed in the bombings and a campus police officer who authorities said was shot by Tsarnaev and his younger brother days later. A memorial service for the officer, 26-year-old Sean Collier, is scheduled for Wednesday. Vice President Joe Biden is expected to speak.

Also Wednesday, Boylston Street, where the blasts occurred, reopened to the public after being closed since the bombings.

While family said that the older Tsarnaev had been influenced by a Muslim convert to follow a strict type of Islam, brother 19-year-old Dzhokhar Tsarnaev remained hospitalized after days of questioning over his role in the attacks. Tamerlan Tsarnaev, 26, was killed in a shootout with police last week.

Conflicting stories appeared to emerge about which agencies knew about Tamerlan Tsarnaev's six-month trip to Russia last year how they handled it. Homeland Security Secretary Janet Napolitano told the Senate Judiciary Committee on immigration legislation that her agency knew about Tsarnaev's journey to his homeland.

But Sen. Lindsey Graham, R-S.C., said the FBI "told me they had no knowledge of him leaving or coming back."

Information-sharing failures between agencies prompted an overhaul of the U.S. intelligence system after the Sept. 11, 2001, terror attacks.

Meanwhile, evidence mounted that Tsarnaev had embraced a radical, anti-American strain of Islam. Family members blamed the influence of a Muslim convert, known only to the family as Misha, for steering him toward a strict type of Islam.

"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.

Authorities don't believe Tsarnaev or his brother had links to terror groups. However, two U.S. officials said that Tsarnaev 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.

Eight-year-old Martin Richard, a Boston schoolboy and the youngest of those killed by the blasts, was laid to rest Tuesday 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."

The Richards family said they would hold a public memorial service for Martin in the coming weeks.

Dzhokhar Tsarnaev's condition was upgraded from serious to fair Tuesday as investigators continued building their case against him.

He could face the death penalty after being charged Monday with joining forces with his brother in setting off shrapnel-packed pressure-cooker bombs. Three people were killed and over 260 injured. About 50 were still hospitalized.

Dzhokhar Tsarnaev was captured hiding in a tarp-covered boat in a suburban Boston backyard on Friday.

In Washington, Senate Intelligence Committee member Richard Burr, R-N.C., said after his panel was briefed by federal law enforcement officials that there is "no question" that Tamerlan Tsarnaev was "the dominant force" behind the attacks and that the brothers had apparently been radicalized by material on the Internet rather than by contact with militant groups overseas.

The brothers' parents are from Dagestan, a predominantly Muslim province in Russia's Caucasus, where Islamic militants have waged an insurgency against Russia. A U.S. Embassy official said Wednesday that a team of U.S. investigators has traveled to Dagestan to speak to the parents. The official spoke on condition of anonymity because he was not authorized to speak to the media.

Family members reached in the U.S. and abroad by The Associated Press said Tamerlan was influenced by 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 that the CIA was behind 9/11.

"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.

Then, 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.

The disclosures about the possible role of Misha in influencing Tsarnaev was described as "new information" by Rep. Bob Goodlatte, R-Va., chairman of the House Judiciary Committee. "It's important we have the appropriate authorities check that out," he said Wednesday on CNN. "Obviously if there are people fomenting that type of activity in the United States we want to know who they are and hold them accountable."

Napolitano said Tuesday that her agency knew of Tamerlan Tsarnaev's trip to Russia. She said that even though the suspect's name was misspelled on a travel document, redundancies in the system allowed his departure to be captured by U.S. authorities in January 2012.

Meanwhile, a U.S. Embassy official said U.S. investigators traveled to southern Russia to speak to the brothers' parents, hoping to learn more about their motives.

In other developments:

— A lawyer for Tamerlan Tsarnaev's wife, Katherine Tsarnaeva, said his client "is doing everything she can to assist with the investigation," although he would not say whether she had spoken with federal authorities. Another lawyer for Tsarnaeva said the 24-year-old deeply mourned the loss of innocent victims in the bombings.

— The Massachusetts 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.

— In New Jersey, the sisters of the suspects, Ailina and Bella Tsarnaeva, issued a statement saying they were saddened to "see so many innocent people hurt after such a callous act." Later, in brief remarks to several news outlets, Ailina described her elder brother as a "kind and loving man." She said of both brothers: "I have no idea what got into them" and also that "at the end of the day no one knows the truth."

— Phantom Fireworks of Seabrook, N.H., said Tamerlan Tsarnaev bought 48 mortar shells at the store in February. Company Vice President William Weimer, however, said the amount of gunpowder that could be extracted from the fireworks would not have been enough for the Boston bombs.

— A fund created to benefit the victims of the Boston Marathon attacks has generated $20 million. Mayor Thomas Menino said more than 50,000 donors from across the world have made donations to One Fund Boston.

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Dozier reported from Washington. Associated Press writers Bridget Murphy and Bob Salsberg in Boston, Lynn Berry in Moscow, and Adam Goldman, Eric Tucker, Matt Apuzzo, and Eileen Sullivan in Washington contributed to this report.

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(Photo: AP Photo/Elise Amendola)