At least one camera in the hallway outside the cell where authorities say registered sex offender Jeffrey Epstein hanged himself earlier this month had footage that is unusable, although other, clearer footage was captured in the area, according to three people briefed on the evidence gathered earlier this month. It was not immediately clear why some video footage outside Epstein's cell is too flawed for investigators to use or what is visible in the other, usable footage. The incident is being investigated by the FBI and the Justice Department's inspector general's office, which are attempting to determine what happened and...