It’s just “preliminary” evidence. Could be that Tamerlan, when he wasn’t busy favoriting Chechen jihadist videos on YouTube, was building up an explosive hatred of marathons.

This AP story is actually newsy, not because of the conclusion officials have drawn but because of how they drew it:

Two U.S. officials say preliminary evidence from an interrogation suggests the suspects in the Boston Marathon attack were motivated by religion but were apparently not tied to any Islamic terrorist groups.

The two ethnic Chechen brothers practiced Islam.

The U.S. officials spoke Monday on condition of anonymity because they were not authorized to publicly discuss the investigation.

Whose interrogation? If they got it from a family member, that’s not news. More than one has already talked to reporters about Tamerlan becoming more religious over the last few years. If they got it from Dzhokhar, obviously that’s big news. Stay tuned.

The NYT has a transcript of today’s bedside magistrate hearing. I knew they’d given him the Miranda warnings but it turns out he got the deluxe version. On page 4, the magistrate warns him three times that he doesn’t have to talk to police. He has a lawyer now too, so let me clip this part in anticipation of the next round of moral peacocking about how they’re denying him access to counsel, etc:

Via Mediaite, here’s a possible lead from CNN. Tamerlan Tsarnaev posted a video last year of a Chechen jihadi who operated out of Dagestan, the same region that Tsarnaev visited in 2012. The Chechen was killed by Russian forces last year. Was the clip inspiration or something more?

Update: Just thinking out loud: It’s possible, although improbable, that Dzhokhar might not know the full extent of Tamerlan’s training, if there was any. That’s not to exculpate him in any way — obviously, if the complaint filed today is true, he knew he was setting off bombs — but it may be that Tamerlan was in touch with people in Dagestan and then trained Dzhokhar over here with whatever expertise he picked up there.

Update: Newsy:

Bombing suspect tells investigators, in writing, brothers conceived attack on their own, motivated by religious fervor – @PeteWilliamsNBC

— NBC Nightly News with Lester Holt (@NBCNightlyNews) April 23, 2013

Update: Here’s why the feds are saying that they think the Tsarnaevs acted alone:

MORE: Bombing suspect tells investigators, in writing, brothers got instructions on how to make bombs from the Internet – @PeteWilliamsNBC

— NBC Nightly News with Lester Holt (@NBCNightlyNews) April 23, 2013