Tsarnaev's parents weren't as devout, she said.
"And it is very strange to me that it was him who adopted Islam, not his father, not his mother, but himself," she said. "But it's not so strange because nowadays the children study Islam and teach their parents, and that's exactly how it turned out with him."
Tsarnaev's behavior made his beliefs clear, she said.
"You know, he and other men don't even touch other women, I mean, he doesn't speak to them (other women)," she recalls. "He could speak to his sisters, his cousins and me, and other women are of no significance to him because it's a sin to even look at other women in the eye."
That faith, Suleimanova said, was one reason she believes there is no way her nephews could be behind the Boston bombings.
"In Islam, killing a non-Muslim is like killing all humanity," she said, "and killing a Muslim is like killing the whole world."
Suleimanova recalled being with Tsarnaev's parents last week as the same grainy pictures of their sons that were broadcast around the world flashed on their television screen.
His father, Anzor Tsarnaev, pointed. He was certain the two men were his sons.
Their mother, Zubeidat Tsarnaeva, the aunt remembered, grabbed the television.
"It can't be, it can't be happening," she screamed. "I don't believe it. Children are dead!"
Earlier that week, Zubeidat had been worried for her sons after hearing about the explosions. When she asked how they were doing in a phone conversation, the brothers said they loved her and that everything was "pretty normal," Suleimanova said.
"Mommy, we are totally fine," they said, according to Suleimanova. "We miss your warmth and your caress."
Russia's fight with Islamic militants
In a building on the other side of the city, the walls are still scarred from a fierce gunbattle between Russian security forces and Islamist militants that erupted last year.
Fallen cinder blocks litter the ground inside.
Neighbors told CNN that Abu Dujana and the other young men who once lived in the building seemed peaceful and ordinary.
But in late December 2012, authorities brought in an armored vehicle to kill Abu Dujana, whose real name was Gadzhimurad Dolgatov.
There are no clues in the rubble left behind that offer answers to a troubling question: Why did Tsarnaev's YouTube page link to the rants of the militant who died here?
In August 2012, soon after returning from Russia to the United States, Tsarnaev apparently created a YouTube channel with links to a number of videos. Two videos under a category labeled "Terrorists" have since been deleted. It's not clear when or by whom.
One of those videos showed Abu Dujana, who led a small militant group that had links to the most potent Islamist group in the region.