The conversations are significant because, had they been revealed earlier, they might have been enough evidence for the FBI to initiate a more thorough investigation of the Tsarnaev family.
Rep. Peter King, a member of the House Homeland Security Committee, told NBC's "Today" show Monday he believes the FBI investigation of the two young men would have gone much further if the Russian government had informed Washington of "the mother's radicalization, the son's radicalization. .. It definitely would have caused the investigation to go further."
Anzor's brother, Ruslan Tsarni, told the AP from his home in Maryland that he believed his former sister-in-law had a "big-time influence" on her older son's growing embrace of his Muslim faith and decision to quit boxing and school.
While Tamerlan was living in Russia for six months in 2012, Zubeidat, who had remained in the U.S., was arrested at a shopping mall in the suburb of Natick, Mass., and accused of trying to shoplift $1,624 worth of women's clothing from a department store.
She failed to appear in court to answer the charges that fall, and instead left the country.