Two Hungarian students, ages 16 and 20, died in the July 7 crash, which plunged 35 passengers and two crew members aboard the stalled duck boat into the swift Delaware River.
"I feel terrible, and my client feels terrible, about the two people who died," DeSimone said Monday.
He said he hopes to have his client speak with investigators someday about the deadly July 7 crash but has so far advised him to remain silent. DeSimone is especially concerned about the relatively low threshold for involuntary manslaughter under federal law.
The federal statute requires only simple negligence, compared with the extreme negligence required under state law for that charge, he said.
The tug pilot, a mate, has not been identified either by authorities or DeSimone. The mate was piloting the tug while the captain was on break, the Coast Guard has said.
In radio communications released Friday, the tug is heard telling the Coast Guard: "We are the ones that, I guess, capsized the duck boat. We're on scene, but we do have a barge alongside so there's not too, too much we can do."
The Coast Guard told the tug's five-man crew to throw lifejackets to survivors.
The National Transportation and Safety Board is preparing a preliminary report based on interviews, post-crash tests of the vessels and other evidence. The report is not likely to be completed before Labor Day, and a final report could take another year, NTSB spokesman Ted Lopatkiewicz said Monday.
The agency then refers any recommendations on criminal charges to federal prosecutors.
On Monday, officials in New Jersey released a recording of a 911 call reporting the collision from that side of the Delaware River.
"A barge just ran over one of the duck boats on the Delaware River. There are people in the water," the caller told a police dispatcher.
The dispatcher put him on hold for more than 40 seconds. He then tried unsuccessfully to transfer the call to Philadelphia police, before giving the caller that number to call.
The duck boat crash occurred near the Philadelphia shoreline. A Philadelphia police marine unit helped pluck some of the survivors from the water, as did a ferry boat crossing the river and bystanders onshore.
DeSimone once represented a club operator charged with involuntary manslaughter in the 2000 collapse of his nightclub, which sat on an aging pier in the Delaware River. Three young women died.
Amid evidence the pier was moving, causing cracks in the floor, the nightclub operator pleaded guilty to three counts of involuntary manslaughter and served nine months of house arrest. The pier owner served house arrest after his no contest plea to those charges and risking a catastrophe.
That case unfolded in state court. The duck boat crash is under federal jurisdiction, in part because of the marine transportation issues involved.
The Hungarian students killed, 16-year-old Dora Schwendtner and 20-year-old Szabolcs Prem, were touring the United States through a church-sponsored exchange program.