In the wake of the Boston Marathon bombings, relatives of now-deceased suspect Tamerlan Tsarnaev blamed his radicalization on a 26-year-old Chechen immigrant, known to Tsarnaev's relatives only as "Misha." "Somehow, he just took his brain," Tamerlan's uncle, Ruslan Tsarni, told the AP. "I heard about nobody else but this convert. The seed for changing his views was planted right there in Cambridge." The man in question has now come forward, and in an exclusive interview with the New York Review of Books, he insists he's no Svengali.

"I wasn’t his teacher," Mikhail Allakhverdov told NYRB from his home in Rhode Island. "If I had been his teacher, I would have made sure he never did anything like this." Allakhverdov insisted he'd never met the Tsarnaev family members who accused him of brainwashing Tamerlan, and said, "I’ve been cooperating entirely with the FBI. I gave them my computer and my phone and everything I wanted to show I haven’t done anything. And they said they are about to return them to me. And the agents who talked told me they are about to close my case."

The FBI has not commented on Allakhverdov beyond acknowledging that they'd located and interviewed him. So far, it still appears that the Tsarnaev brothers acted alone in the attack without assistance from outside terrorist groups. Democratic Senator Claire McCaskill, who was briefed by investigators, says there was no evidence that the brothers "were part of a larger organization, that they were, in fact, part of some kind of terror cell or any kind of direction."

But Texas Republican Rep. Michael McCaul isn't convinced the brothers acted alone. "Are they overseas in the Chechen region or are they in the United States?" McCaul asked on Fox News Sunday. "In my conversations with the FBI, that's the big question. They've casted a wide net both overseas and in the United States to find out where this person is. But I think the experts all agree that there is someone who did train these two individuals."

Meanwhile, the boys' father, Anzor Tsarnaev, has canceled plans to return to the U.S. from Russia to reclaim his son's body and visit his surviving son, who has been moved to a small, solitary cell with a steel door at a federal medical detention center outside Boston. "I am not going back to the United States. For now I am here. I am ill," Tsarnaev told reporters. "Unfortunately I can't help my child in any way. I am in touch with Dzhokhar's and my own lawyers. They told me they would let me know (what to do)."

Anzor Tsarnaev's remarks came after it was revealed that Tamerlan had been recorded talking about "jihad" in at least one telephone conversation with his mother Zubeidat Tsarnaeva. Though they alerted the FBI about Tamerlan multiple times, it seems that Russian intelligence never shared the specifics of the conversations until after the bombings, despite repeated requests from the FBI for more information regarding what was said in those calls.

Rep. McCaul told Fox News Sunday that he thinks the suspects' mother, Zubeidat Tsarnaeva, played "a very strong role" in her Muslim sons' radicalization process and promised that she'd be held for questioning if she returned to the U.S.