After last week's Boston Marathon bombings, Zubeidat Tsarnaeva phoned her son Tamerlan in Massachusetts to make sure he was safe.

"Mama, why are you worrying?" Tamerlan replied from Boston, laughing.

Days later, it was the son who phoned his mother. The two, in recent years, had shared a powerful transformation to a more intense brand of Islam.

"The police, they have started shooting at us, they are chasing us," Mrs. Tsarnaeva says Tamerlan told her. "Mama, I love you." Then the phone went silent.

Soon, Tamerlan Tsarnaev, 26 years old and a prime suspect in the bloody marathon bombings, was dead. Within hours, his younger brother and alleged accomplice, 19-year-old Dzhokhar, was severely wounded but in custody after a police manhunt found him hiding under a tarp in a boat called the Slipaway II in Watertown, Mass.