A fourth victim from last month's Baltimore bridge collapse has been recovered after salvage crews located the body trapped in one of the missing construction vehicles underwater.
Six people died when the Francis Scott Key Bridge fell on 26 March after it was struck by a large container ship.
The FBI has opened a criminal investigation into the incident, sources told the OceanNewsUK's US partner CBS.
It will examine the circumstances leading up to the incident.
Federal agents have been present at the site since that time, the sources said.
Eight construction workers were on the bridge when it was struck by the Dali container vessel, plunging them into the waters below.
Two were rescued on the day while the bodies of two more were recovered two days later. A third body, that of Maynor Yasir Suazo Sandoval, was found earlier this month.
The fourth victim was positively identified on Monday by the chief medical examiner's office, a day after the remains were recovered.
The family does not want the name to be released, said officials leading the salvage work.
"As we mourn the lives lost and continue the recovery operation, we recognise each missing individual is someone's beloved friend or family member," said Colonel Roland Butler, Jr, superintendent of the Maryland Department of State Police, on Monday evening.
Also on Monday, a spokesperson for the Department of Justice confirmed the "FBI is present aboard the cargo ship Dali conducting court-authorised law enforcement activity".
No further information will be shared publicly on the investigation at this time, the spokesperson said.
Erek Barron, the US Attorney in Maryland who is aiding the FBI investigation, said his office would not comment.
But he said "the public should know, whether it's gun violence, civil rights abuse, financial fraud, or any other threat to public safety or property, we will seek accountability for anyone who may be responsible".
The salvage mission includes the US Army Corps of Engineers, the Navy, the Coast Guard and Maryland authorities. It is ongoing to recover the last two victims and parts of the bridge.
The FBI investigation is separate from an ongoing probe by the National Transportation Safety Board (NTSB).
Meanwhile, Baltimore Mayor Brandon Scott announced his city was taking "legal steps" to address the collapse.
Mr Scott said two national law firms will take "action to hold the wrongdoers responsible, and to mitigate the immediate and long-term harm caused to Baltimore City residents".
He said the aim was to hold "all entities accountable", including the owner, charterer, manager and operator of the Dali ship, as well as potentially liable third parties.
Most of the 47-year-old bridge collapsed when it was struck by the Dali - a 948ft (289m) cargo ship - in the early hours, plunging men who were working on maintenance at the time into the Patapsco river.
Investigators have also recovered the data recorder of the ship, which they hope may explain the catastrophic power failure that caused it to go off course and hit the bridge.
Officials said the ship had been moving at eight knots, or roughly 9mph (15km/h).
Jennifer Homandy, head of the NTSB, has said one of the factors under investigation is whether contaminated fuel played a role in the vessel losing power.
A mayday signal was sent when the ship was approaching the bridge, authorities had said, which gave authorities time to stop cars driving on to the bridge.
The collapse led to the closure of the Port of Baltimore, one of the busiest in the US and a key hub for the transport of vehicles.
Two alternative channels have since been opened as the salvage operation continues.
