Boston bomb scene reopens to residents, business owners

(CNN) -- Eight days after twin bomb blasts at the Boston Marathon killed three, injured more than 260 and disrupted the normal routines of countless others, authorities slowly began allowing residents and business owners back into the area Tuesday.

Those who live in the area and own businesses there were being allowed to stay, but there was no word on when the street where the bombings occurred will be once again fully open to the public. That, the city says, will depend on how quickly building owners can make repairs and other issues.

The staged opening is the latest sign that Boston is working hard to return to normal after an extraordinary week that began with the bombings near the annual race's finish line and ended with a dramatic manhunt that all but locked down the nation's fifth largest metro area for the better part of a day.

Also Tuesday, candidates to fill the state's vacant U.S. Senate seat resumed their campaigns, which had been suspended in the wake of the bombing.

Meanwhile, the family of slain Massachusetts Institute of Technology police Officer Sean Collier will lay him to rest Tuesday in a private memorial service in Stoneham, Massachusetts, CNN affiliate WHDH reported.

A public memorial service is scheduled for Wednesday on MIT's campus, the station said.

New details on officer's saying

Collier was killed Thursday night, near the beginning of the wild 24 hours that culminated in 19-year-old bombing suspect Dzhokhar Tsarnaev's capture in the backyard of a Watertown, Massachusetts, home where he had been hiding in a boat.

Authorities suspect Tsarnaev and his 26-year-old brother, Tamerlan Tsarnaev, of killing the officer. The older brother later died in a shootout with police. Dzhokhar Tsarnaev has not been charged in the officer's death.

According to a source with direct knowledge of the investigation, Collier didn't even have time to activate his emergency alert before being shot four or five times in the chest and head as he sat in his patrol car on the MIT campus. It took officers 13 minutes to reach Collier after 911 calls came in about the shooting, authorities said.

It's not clear why the brothers allegedly ambushed the officer, the source said.

The source said investigators believe the Tsarnaevs then carjacked a black SUV, took the driver hostage and drove past the scene of the shooting before going to a gas station.

Carjacking victim speaks

In an exclusive interview with CNN affiliate WMUR, a man identifying himself as the carjacking victim said he was worried for his life.

"They asked me where I'm from. I told them I'm Chinese," WMUR quoted the man as saying. "I was very scared. I asked them if they were going to hurt me. They said they won't hurt me. I was thinking, 'I think they will kill me later.'"

The man escaped when the brothers stopped to fill up the gas tank, running for his life as one of the brothers swore at him, WMUR reported.

Soon after, the brothers encountered police, setting off a furious gun battle in which authorities say they fired handguns and hurled explosives at pursuing officers before Tamerlan Tsarnaev was shot. As the younger brother fled in the vehicle, he apparently ran over Tamerlan, authorities said.

Self-radicalized?

Dzhokhar Tsarnaev has indicated that his older brother, not any international terrorist group, masterminded the deadly attack, a U.S. government source said.

Tsarnaev, who has been hospitalized with a tube down his throat since Friday, communicated with investigators by writing and nodding.

The preliminary interviews with Tsarnaev suggest the two brothers fit the classification of self-radicalized jihadists, the government source said.

Tsarnaev has conveyed to investigators that Tamerlan's motivation stemmed from jihadist thought and the idea that Islam is under attack, and jihadists need to fight back, the source said Monday.

The government source cautioned that the interviews were preliminary, and that Tsarnaev's account needs to be checked out and followed up on by investigators.

A federal law enforcement official told CNN that while investigators have seen no indication the suspects collaborated with others, they still have plenty of work to do before they can confidently say no one else was involved in the April 15 attack.

That official would not comment on any motive or specifics on what Dzhokhar Tsarnaev has communicated to officials.

A senior administration officials told CNN's Barabar Starr Tuesday that investigators are trying to determine whether Inspire magazine, the online magazine published by al Qaeda in Yemen, was the blueprint for the bombs.

But "numerous sources" could have provided such information, the source stressed.

A bedside court appearance

The younger Tsarnaev has been charged with using and conspiring to use a weapon of mass destruction resulting in death, as well as one count of malicious destruction of property by means of an explosive device resulting in death.

He was shot in the head, neck, legs and one hand, according to an FBI affidavit supporting the charges. It's not clear whether he was wounded during his capture Friday night or in the earlier shootout with police.

Although he had been heavily sedated and on a ventilator at Beth Israel Deaconess Medical Center, Tsarnaev was "alert, mentally competent and lucid" during the brief initial court appearance at his bedside Monday, U.S. Magistrate Judge Marianne Bowler found.

During the hearing, Tsarnaev communicated mostly by nodding his head, although he once answered "no" when Bowler asked him if he could afford a lawyer, according to a transcript of the proceeding. A public defender was appointed to represent him.

Investigators have been asking Tsarnaev whether there are more bombs, explosives caches or weapons beyond those already found by police, and if anyone else was involved in the attacks, a source with direct knowledge of the investigation told CNN. Investigators are going into Tsarnaev's room every few hours to ask questions in the presence of doctors, the source said.

Federal agents at first questioned Tsarnaev without reading him his Miranda rights, under an exception to the rule invoked when authorities believe there is an imminent public safety threat, a Justice Department official said over the weekend.

By the time of the hospital room proceeding, government sources said he had been read his rights, and Bowler reviewed those with him again Monday.

Bowler scheduled a probable cause hearing May 30.

Tracing Tamerlan Tsarnaev's background

While Tamerlan Tsarnaev apparently became increasingly radical in the past three or four years, there was no evidence Monday that he had any active association with international jihadist groups.

The Tsarnaev family is from the Russian republic of Chechnya and fled the brutal wars there in the 1990s. The two brothers were born in Kyrgyzstan; Dzhokhar became a U.S. citizen in 2012, while Tamerlan was a legal U.S. resident.

An FBI official said agents interviewed Tamerlan Tsarnaev in 2011 at the request of the Russian government. The FBI said Russia claimed that he was a follower of radical Islam and that he had changed drastically since 2010.

But the Russian government's request was vague, a U.S. official and a law enforcement source said Sunday. The lack of specifics limited how much the FBI was able to investigate Tamerlan, the law enforcement official said.

On Tuesday, Tamerlan Tsarnaev's wife issued a statement through her attorney's office saying she is "doing everything she can to assist with the investigation" and said she and her family are shocked and distraught.

"The reports of involvement by her husband and brother-in-law came as an absolute shock to them all," the statement said.

Suspects' mother reacts

The suspects' mother, Zubeidat Tsarnaev, said Tuesday that she believed her sons had been framed.

Tsarnaev said she believes a conspiracy is at work against her sons, and she doesn't believe evidence put forward by U.S. investigators in alleging their involvement in the bomb plot.

Speaking from her home in Dagestan -- a Russian republic on the Caspian Sea -- Tsarnaev said she didn't believe her older son was dead until she saw images of his body Monday night on the Internet.

She thinks he died because he was a Muslim and charged that authorities silenced her younger son to prevent him from defending himself.

She said family members have arranged for Tamerlan Tsarnaev to be buried at a mosque in Cambridge, Massachusetts, Tuesday or Wednesday.