The tugboat mate who pleaded the fifth earlier this week when federal investigators inquired about the deadly Duck-boat accident was relieved of duty Tuesday night by the vessel's operator, K-Sea Transportation.

The mate, who has not been identified by the company, continues to be a paid employee of K-Sea Transportation, which has "assisted the mate of the Caribbean Sea [the tugboat's name] in retaining independent legal counsel," according to a statement from the East Brunswick, N.J.-based company.

That lawyer, Frank DeSimone, had no comment last night when contacted at his home. But he did say that he had advised his client, whom he refused to identify, to plead the Fifth Amendment, the right against self-incrimination, when meeting with officials from the National Transportation Safety Board.

DeSimone, who said that he has experience in maritime law, refused to say when he was contacted by the mate.

It is believed the mate was at the helm when the 75-foot vessel pushed the 250-foot barge, The Resource, over the anchored Duck boat. The boat sank, leading to the death of two Hungarian students - Szabolcs Prem, 20, and Dora Schwendtner, 16.

Duck-boat crew members tried to radio the Caribbean Sea on Channel 13, but the tug didn't respond to the calls, the NTSB said.

When told that the mate had been relieved of duty, a veteran official with the Seafarer's International Union declared: "Oh, he's gonna to lose his license. He's lost his career, especially because he didn't speak up.

"You gotta tell the truth to the Coast Guard," said the man, who spoke on condition of anonymity.

He said that the pilot should have heard the calls from the Duck-boat crew. "Plus, he should have seen that coming down the river, and if it's the mate, the mate was wrong," he said. "How can it be the Duck boat's fault?"

New York personal-injury lawyers Peter and Holly Ronai, hired by the Hungarian students' families, probably know where to lay the blame.

The husband-and-wife legal team, based in Manhattan, will represent the Schwendtners and the Prems in a possible civil action, the Inquirer reported last night.

"The families are devastated. They're completely devastated," Peter Ronai told the paper. The Ronais were about to return from their vacation in Hungary when Peter Ronai was contacted by a friend of Peter Schwendtner, Dora's father. Peter Ronai stayed and Holly Ronai came back last week, the Inquirer said.

He has met with the families to discuss court actions, although it's not just about money.

"There may be criminal proceedings as well," Ronai said. "Dora's father wants the people responsible for this put in jail."

Meanwhile, the NTSB performed a test using a Ride the Ducks amphibious vehicle yesterday. The Duck boat spent 45 minutes in the Delaware River, twice heading south toward the Hyatt Regency on Penn's Landing and then back north to the Benjamin Franklin Bridge.

NTSB spokesman Ted Lopathkiewicz said that the results of the ongoing tests would not be immediately released.

Staff writer Josh Fernandez contributed to this report.