They were college buddies, though it seems like only Tsarnaev and Tazhayakov were the only ones enrolled this past semester. According to the AP report from April 27, "Kadyrbayev is no longer enrolled; he was last a student in the fall. Tazhayakov is enrolled."

That tidbit about enrollment — and, importantly, Kadyrbayev not being a student — could have been a red flag, since both suspects were in this country on student visas. As NBC's Pete Williams reports, Tazhayakov and Kadyrbayev were under investigation for not attending classes:

.@petewilliamsnbc on the new suspects: They were under investigation for not attending classes — Sarah Boxer (@Sarah_Boxer) May 1, 2013

To that end, CNN's Jake Tapper notes that Tazhayakov may have broken his immigration status:

The first US government official told CNN that at an immigration court hearing this morning, the court learned that Tazhayakov returned to Kazakhstan in December 2012, and his status with U. Mass-Dartmouth was terminated on January 3. Yet somehow he was allowed to return into the U.S. on January 20.

Here's Dias and Dzhokhar in a photo that's already in question for its social media deletion:

Dias is also apparently pictured in this photo with Tsarnaev, from Tsarnaev's much parsed account on Vkontakte (or VK), Russia's equivalent of Facebook. We had found this photo during our initial search for information on Dzhokhar's social media accounts:

The photo no longer shows up on Dzhokhar's page, or on Kadyrbayev's page. (The two were both tagged, so it showed up on both profile pages, just like Facebook, but in Kadyrbayev's case it was a profile photo — see below for more.) And CNN is reporting that the photo was deleted:

CNN: New Boston suspect deleted photo with Tsarnaev brother after marathon attack — Jon Passantino (@passantino) May 1, 2013

That's significant in that — depending on the timing, and whether it was deleted before or after Tsarnaev's name was released two Thursday ago — the photo could show that Dias knew Tsarnaev was a suspect. And that could possibly show that the roommates knew what they were doing if they were moving items from Tsarnaev's room — aiding a suspect is a big charge in question so far.

According to the criminal complaint against him and his roommate, Kadyrbayev exchanged texts with Tsarnaev that Dzhokhar looked like the suspect the FBI identified:

That's where the timing gets very, very interesting: As we mentioned, Kadyrbayev deleted his photo with Dzhokhar. What's fishy is that Kadyrbayev deleted the photo at around 3 a.m. on the morning of April 19, according to CNN, during the wild night of mayhem in Boston and after Dzhokhar's photo had been released — but before the rest of the world knew that Dzhokhar Tsarnaev was a suspect. Here's that photo on Kadyrbayev's VK profile wall, from sometime before that deletion: