The tracking number on the package that didn't go boom from yesterday would be my guess. Tracked to the exact time/place of drop-off. Narrows down the video image timeframe to a precise time, and they've got their best potential suspect standing there dropping it off. Other video outside the store likely captured the vehicle/plates.
I forgot about the one that didn’t go boom. Good point. He’d be a real idiot to leave a trail that can be followed — tracking numbers, addresses, security cameras, vehicle plates, etc. But he turned to crime / terrorism, so not the sharpest pencil in the box.