A lawyer for the pilot of the tug pushing a barge that sank a duck boat in Philadelphia fears his client could face felony charges under federal law.

Lawyer Frank DeSimone says he hopes someday to have his client speak with investigators about the July 7 crash, despite his advice to date to remain silent.

DeSimone says his client feels terrible about the deaths of two Hungarian students aboard the tour boat.

But he says prosecutors need only accuse his client of simple negligence to bring involuntary manslaughter charges under federal law. State law typically requires an extreme negligence finding.

The client has not been identified by name.

Also Monday, officials in New Jersey released a recording of a 911 call reporting the collision from that side of the Delaware River.