U.S. investigators are going to Russia and back to press the parents of the Boston bombing suspects, seeking private answers after their absurdist public standoff — and countering interviews full of conspiracies and coverups with questions about an extremist trail gone cold but not yet frozen.

Investigators from the American embassy in Moscow arrived in Dagestan this week, reports CNN, but that "conversation" with the parents is apparently over. USA Today says the mother, Zubeidat Tsarnaeva, has been interviewed "at length" in that same souther Russian region, with FBI officials — already under scrutiny at home and running into dead ends in their bedside questioning of Dzhokhar Tsarnaev — working with Russian officials looking for the foundations of radicalization, and perhaps ties abroad. And after Tuesday's questioning there, the Associated Press reported late Wednesday morning that the Zubeidat spent all day in Russia's FSB security building while the father, Anzor Tsarnaev, was feeling too ill for questioning there; both parents will travel to the U.S. on Thursday, the AP reports, though U.S. officials may stay in town.

If FBI agents, other American investigators and diplomats, or Russian security forces are trying to change the hearts and minds of the two parents, it won't be easy: In bizarre media interviews since their sons' names surfaced Friday, they have expressed disbelief, and charged the U.S. government with some sort of setup aimed at Chechnya. Those stances haven't changed, at least in public, raising questions about how well the separated couple really knew their sons of late, or if they could provide useful answers about potential terror links abroad. The mother is facing legal troubles of her own, and in a televised interview with Britain's Channel 4, the mother insists that "I know my kids":

Hearts and minds may not be the goal of prying investigators, who already have plenty of signs of guilt from the younger Tsarnaev's initial hearings at Boston's Beth Israel Deaconess Medical Center, where he remains in "fair" condition. While Dzhokhar reportedly maintains that the brothers acted alone, the AP reports that officials want to know much more about both brothers' links back to home, despite being in the U.S. for so long:

Investigators are looking into whether Tamerlan Tsarnaev, who spent six months in Russia's Caucasus in 2012, was influenced by the religious extremists who have waged an insurgency against Russian security services in the area for years. The brothers have roots in Dagestan and neighboring Chechnya, but neither spent much time in either place before the family moved to the United States a decade ago.

And as ABC News's Kirit Radia explains, investigators aren't looking for more suspects; they're looking for leads about organizations that Tamerlan may have aligned himself with. Indeed, "no known organizations" has been the key phrase coming from law enforcement officials reporting from the ongoing investigation — and there's reason to believe the U.S. delegation would pursue every lead on any organization not currently on their radar. From ABC:

Specifically they want to know if Tamerlan, who began linking to Islamic extremist web videos on YouTube after the trip, met any radicals or militants during his trip. The head of Russia's Interpol branch said Monday they were not searching for anyone new in connection with the Boston bombing.

Indeed, beyond Tamerlan's favorite YouTube videos and the magazine that may have helped the brothers build explosives, there is a new online trail and a mysterious character of interest named Misha, an Armenian muslim who is now believed to have helped radicalize the older brother. So investigators are hoping for a lot more clarity than what the parents have been telling the Western media. "Nonsense. He was just a friend," Zubeidat told ABC News of Misha, in an interview before her second day of questioning in Dagestan. The ABC report this morning added: "Tsarnaeva said Misha knew a lot about Islam and that it was interesting to learn from him, but denied his views were extreme." ABC added. Indeed, judging from the mother's public interviews, it appears her threshold of extremism seems to be a bit high — "Reading extremist materials does not make you a terrorist," the Daily Telegraph quotes her as saying — but maybe the private questioning from local and foreign officials will go better on the ground.

There's little word from how the questioning in Dagestan is going, other than the AP's description from a friend:

Heda Saratova, a prominent Chechen rights activist providing support to the distraught mother, said Tsarnaeva first went in for questioning on Tuesday, returning late at night. Saratova said she had no details about the discussions, but Tsarnaeva said they were "cordial."

As for the boys' father, it's unclear how much of a role he even had in their lives these last few years. On Friday, Anzor told the AP that Dzhokhar was a second-year medical student — he turned out to be an undergraduate sophomore weed dealer with bad grades — and Anzor's own brother (yes, that one) says the Tsarnaev patriarch "lost control over that family a long time ago." It's becoming increasingly clear, at least on the outside, that Anzor Tsarnaev and Zubeidat Tsarnaeva may have just been bad — or at least out-of-touch — parents. As William Saletan writes in a thorough piece over at Slate:

You can’t expect witnesses to report every fanatical outburst to the FBI. But when family members are repeatedly exposed to signs that a loved one is drifting into the vortex of violent extremism, they have a duty to intervene, or at least to alert someone. If they don’t, and the fanatic becomes a killer, they bear an awful responsibility. If they deny that responsibility by accusing the police and the government of anti-Islamic conspiracies, they forfeit our sympathy, our respect, and our trust. Police your family. Police your congregation. Police your community. If you don’t, the rest of us will do it for you.

Now, it appears, the authorities are trying to hold the parents responsible for handing over better information.