I know there are tons of photos of people with backpacks, but these are the two who are said to be "persons of interest" the FBI is looking for now based on the surveillance footage from Lord and Taylor and the local TV footage the FBI looked at.
They didn't fully release it. Another site has been posting tons of pictures of any and everyone with black/dark bags. A news report tonight mentioned they saw the footage of the two "persons and interest" and it describes these two perfectly.
Thank you for bringing this nonsense full circle. I was just about to believe you when you posted the pictures with the badass evidence of the backpack being gone (it looked heavy). But, then, I saw that the other guy's shoulder bag was still there so I figured, nah, couldn't be them since if they had been collaborating he would be the second bomb dude, so I started doubting you. But, just as soon as I had doubt you posted a reddit link. Brought me right back in.
Apparently one of these guys is the one seen on the surveillance footage leaving his bag at bomb site 2 not long before the 2nd explosion. Coupled with the fact they were both seen with the same bags earlier right at bomb site 1 and their bags are big enough to hold the pressure cooker, that's why they are wanted for questioning.