An employee of the company developing the National Harbor resort in Prince George's County is under investigation for cutting down a tree on the property that may have held a bald eagle's nest.

The U.S. Fish and Wildlife Service is conducting the investigation and has referred the case to the U.S. attorney's office in Baltimore, federal authorities said.

It is a federal crime under the Bald and Golden Eagle Protection Act to disturb the habitat of a bald eagle. Bald eagles also are protected under the Endangered Species Act. Violators can be fined $5,000 or sentenced to one year in prison.

No criminal charges have been filed against the employee of the Northern Virginia-based Peterson Cos. The employee's name is being withheld by investigators.

Developer Milton V. Peterson, the company owner, expressed regret over the incident yesterday in a sometimes tearful interview and said he would take full responsibility for the actions of his employee.

"I sincerely apologize to the community at large and to the thousands of people who have supported us to bring our vision of National Harbor to Prince George's County," he said. "It is a very unfortunate mistake and error in construction."

No birds appeared to inhabit the nest at the time the tree was cut down.

The fallen nest was one of at least two located in the National Harbor project area in Oxon Hill along the Potomac River. A much larger nest that biologists have confirmed belongs to a pair of bald eagles is visible to motorists from the Capital Beltway near the Woodrow Wilson Bridge.

Chris Wagnon, natural resources chief for the county, said it is common for bald eagles to build several nests in an area as a way to trick predators with a "dummy nest."

"There may be a second nest, one that we're not aware of," he said.

Environmentalists and opponents of the resort used the presence of the eagles last year to rally against the development, which has since been approved. They nicknamed the man-made inlet at the site "Eagle Cove" as a way to mobilize resistance.

"They couldn't care less about the environment as a whole, and the eagles are a perfect symbol why the area should be cared for as the natural habitat that it is," said Helen O'Leary, president of the Indian Head Highway Area Action Council, an opposition group.

The developer has permission to grade the land in preparation for construction of the giant entertainment complex. Peterson said his employee was clearing underbrush two weeks ago and accidentally cut down two trees, one containing a nest.

A WTTG-Channel 5 news helicopter crew videotaped the fallen nest after previously videotaping it in the tree.

Peterson defended his company's environmental record and said he is "optimistic that this unfortunate incident shall be resolved so we may proceed with our plans."

Last spring, when the other nest was spotted, Peterson's company agreed to move a construction access road so the eagles would not be disturbed.

Nathaniel K. Tutt Jr., president of the South County Economic Development Association, said he will continue to support Peterson because he believes the development is good for the county.

"The environmentalists will look for anything they can find as a way to derail the project," he said. "If Peterson accidentally cut a tree down, I know everyone, including Peterson, would be very sorry this happened.