Federal law enforcement investigating Baltimore bridge collapse, sources say

Federal law enforcement authorities are investigating the events that preceded the collapse of the Francis Scott Key Bridge in Baltimore, according to two people familiar with the matter. 

The FBI currently has agents on the Dali, the shipping vessel that collided with the bridge, a noted change in posture. 

The investigation, which appears to be separate from the ongoing National Transportation Safety Board probe, is being conducted by Maryland's U.S. Attorney's Office and the FBI, entities that have had representatives at the crash site for weeks.