Two-year-old Wesley Brillant of Natick, Massachusetts kneels in front of a memorial to the victims of the Boston Marathon bombings near the scene of the blasts on Boylston Street in Boston, Massachusetts, April 21, 2013. [Photo/Agencies]

In an interview with The Associated Press, the parents of Tamerlan Tsarnaev insisted Sunday that he came to Dagestan and Chechnya from January to July last year to visit relatives and had nothing to do with the Islamic militants operating in this volatile region in southern Russia. His father said his son slept much of the time.

When the two ethnic Chechen suspects were identified, the FBI said it reviewed its records and found that in early 2011, a foreign government - which law enforcement officials confirmed was Russia - had asked for information about Tamerlan Tsarnaev. The FBI said it was told that Tsarnaev was a "follower of radical Islam" and was preparing to travel to this foreign country to join unspecified underground groups.

The FBI said that it responded by interviewing Tsarnaev and family members, but found no terrorism activity.

No evidence has emerged since to link Tsarnaev to militant groups in Russia's Caucasus. And on Sunday the Caucasus Emirate, which Russia and the US consider a terrorist organization, denied involvement in the Boston attack.

Chechnya has been the scene of two wars between Russian forces and separatists since 1994. That spawned an Islamic insurgency that has spread throughout Russia's Caucasus, with the worst of the violence now in Dagestan.

Despite the violence in Dagestan, Anzor Tsarnaev said Sunday that his son did not want to leave and had thoughts on how he could go into business. But the father said he encouraged him to go back to the United States and try to get citizenship.  

Investigators have not offered a motive for the Boston attack. But in interviews with officials and those who knew the Tsarnaevs, a picture has emerged of the older brother as someone embittered toward the US, increasingly vehement in his Muslim faith and influential over his younger brother.

Across the rattled streets of Boston, churches opened their doors to remember the dead and ease the grief of the living.

At the Cathedral of the Holy Cross in South Boston, photographs of the three people killed in the marathon attack, including a 23-year-old Chinese student, and a Massachusetts Institute of Technology police officer slain Thursday were displayed on the altar, each face illuminated by a glowing white pillar candle.

"I hope we can all heal and move forward," said Kelly McKernan, who was crying as she left the service. "And obviously, the Mass today was a first step for us in that direction."

A six-block segment of Boylston Street, where the bombs were detonated, remained closed Sunday. But city officials were mapping out a plan to reopen it.

Mayor Thomas Menino said Sunday that once the scene is released by the FBI, the city will follow a five-step process, including environmental testing and a safety assessment of buildings. The exact timetable was uncertain.