The daunting task of sifting through thousands of images of the Boston Marathon bombing site in search of a culprit suddenly telescoped to a single video from a Lord & Taylor security camera Wednesday. The second full day of the investigation into the attack that killed three people and injured at least 176 brought jitters, rumors and at least the hope that investigators had made important progress, though Massachusetts Gov. Deval L. Patrick (D) said that while the probe is “making some progress . . . it’s going to be slow, it’s going to be methodical.”

Read below for full developments through Thursday evening.

[liveblog]