A 31-year-old Rockland man pleaded guilty Thursday in federal court to making a false distress call to the Coast Guard, which resulted in a large search effort.

Nathan Libby pleaded guilty June 3 in U.S. District Court in Portland to communicating a false distress call Dec. 3, 2020.

Libby faces up to five years in prison and a $250,000 fine if convicted of the crime.

“I applaud the collaborative efforts of the Department of Justice, Maine Marine Patrol, Rockland Police Department, and the United States Coast Guard in bringing this case to a close and ensuring accountability for Mr. Libby’s actions,” said Capt. Brian LeFebvre, Sector Commander of Coast Guard Sector Northern New England. “Hoax calls like the call Mr. Libby placed unnecessarily put our rescue crews at risk, waste resources, and may limit our ability to respond to actual emergencies.”

He will be sentenced after the completion of a pre-sentence investigation report by the U.S. Probation Office. A federal district court judge will determine any sentence after considering the U.S. Sentencing Guidelines and other statutory factors.

An affidavit filed in court by Coast Guard Investigative Service Special Agent Mark Root detailed the investigation that led to the charge against Libby.

The Coast Guard received a May Day call shortly after 6:30 a.m. Dec. 3, 2020, on VHF marine radio channel 16, The Coast Guard dispatcher spoke with a man for about one to two minutes during the time where the unidentified man said the boat he was on lost its rudder and was taking on water fast, and the pumps could not keep up with the water.

The man said there were three people aboard the boat, and they were in Spruce Head Harbor and trying to get to the Atwood float.

Marine Patrol Officer Nicholas Stillwell responded to Atwood Lobster Co.'s wharf on Spruce Head Island in South Thomaston and boarded a private vessel in an attempt to locate the boat that made the distress call. No vessel was located.

Stillwell returned to the dock and spoke to Libby, who was a dock worker at the neighboring Spruce Head Fisherman's Co-op. Libby provided the Marine Patrol officer a list of boats that went out that morning.

The officer then spoke to someone else at the co-op and played the recording of the distress call. That person said the voice sounded like Libby. The officer went back and spoke to Libby, who said he heard the distress call. He also acknowledged the co-op office had a VHF radio, which was on channel 16.

The officer taped Libby and his voice was compared to the distress call by an associate research professor at the Language Technologies Institute School of Computer Science at Carnegie Mellon University in Pittsburgh. Associate Professor Rita Singh concluded the voice on the distress call was the same as Libby's voice, the affidavit stated.

Surveillance video showed Libby was at the co-op office the time the distress call was made. A check from a radio tower showed the call came from the direction of the co-op.

The Coast Guard sent out a vessel that searched for more than four hours, and a helicopter from Coast Guard Air Station Cape Cod spent more than five hours in the search; Maine Marine Patrol and private boats also helped in the search.

The distress call was also made less than two weeks after the Portland-based fishing boat Emmy Rose sank off the coast of Massachusetts, with four crew members aboard.