CBS brings us this interesting tidbit from the what-if files of the Boston Marathon bombing investigation — as in, what if the Russians had shared this information in 2011 along with its allegedly cryptic warning about Tamerlan Tsarnaev? Would it have prompted a closer look — and was there anything at which to look at the time, anyway?  The information might have allowed the FBI to connect another dot, though:

Russian authorities secretly recorded a telephone conversation in 2011 in which one of the Boston bombing suspects had a conversation with his mother of a radical nature, officials confirmed to CBS News correspondent Bob Orr Saturday, days after the U.S. government finally received details about the call.

In another conversation, the mother of now-dead bombing suspect Tamerlan Tsarnaev was recorded talking to someone in southern Russia who is under FBI investigation in an unrelated case, officials told The Associated Press.

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.

As it was, Russian authorities told the FBI only that they had concerns that Tamerlan and his mother were religious extremists. With no additional information, the FBI conducted a limited inquiry and closed the case in June 2011.

Are we still sure that the other case is unrelated? There seems to be at least one connection between the two.  The interest in southern Russia apart from the Tsarnaev plot appears to indicate that the Caucasus is more of a security concern to the US than first thought.

So what did Tamerlan discuss with his mom on that wiretapped telephone conversation? Three guesses:

RUSSIAN authorities secretly recorded a telephone conversation in 2011 in which one of the Boston bombing suspects vaguely discussed jihad with his mother, officials say. …

In early 2011, the Russian FSB internal security service intercepted a conversation between Tamerlan and his mother vaguely discussing jihad, according to US officials who spoke on condition of anonymity.

The two discussed the possibility of Tamerlan going to Palestine, but he told his mother he didn’t speak the language there, according to the officials, who reviewed the information Russia shared with the US.

In a second call, Zubeidat Tsarnaeva spoke with a man in the Caucasus region of Russia who was under FBI investigation.

Nothing in the conversation suggested a plot inside the US, officials said.

As CBS notes, the FBI has impounded the boat in which Dzhokhar Tsarnaev was captured, and also reports again that Dzhokhar was unarmed — which disputes what the Watertown PD chief told the media on Friday.  The FBI has also finished its search of a dump, but isn’t talking about what it might have found:

One of the latest focuses of the probe has been a landfill in New Bedford, Massachusetts, a city adjacent to the town where the surviving bombing suspect, Dzhokhar Tsarnaev, attended school at the University of Massachusetts-Dartmouth.

Authorities have finished combing the dump for clues that may shed light on the bloody attack, said FBI spokeswoman Laura Eimiller, who wouldn’t say whether they turned up anything.

That includes any luck in locating Tsarnaev’s laptop computer, which a law enforcement official with knowledge of the investigation had said investigators were looking for.

Tsarnaev led authorities to look there, the source said, and others who may have knowledge of the computer’s whereabouts or may have played a role in disposing it also provided leads that prompted the search.