(CNN) -- The U.S. Coast Guard says it has linked six bogus Mayday calls for help in Maryland to the same person, and officials are now asking the public for help finding the suspect. Investigators have determined the calls, which began in May and abruptly ended June 1, came from an area near Little River, Maryland, a small town near Baltimore on the northern tip of the Chesapeake Bay.
"We received two quick 'Mayday, Mayday' calls each time and when we would engage him he would go silent and say nothing else," said the Coast Guard's Jonathan Lindberg.
The Coast Guard delayed alerting the public until it was certain the same person was responsible for the phony cries for help, Lindberg said.
"Making false distress calls limits the Coast Guard and our rescue partners' capabilities to assist those boaters that are in actual emergency situations," said Capt. Kevin Kiefer, commander of Sector Baltimore.
"Hoax radio calls also place first responders in unnecessary danger as they work to assist the boating public," Kiefer added in a statement.
Dealing with fake distress calls is a chronic problem for the Coast Guard, and the cases prove hard to solve. Tracing radio calls is an imperfect science, and authorities lean heavily on the public for information.
In June, a false distress call of a yacht explosion prompted a massive rescue effort off the coast of New Jersey and garnered attention nationwide. As part of the New Jersey investigation, authorities released an audio excerpt from the fake call. On the recording, a male voice is heard saying, "We have 21 souls on board, 20 in the water right now. I have three deceased on board, nine injured because of the explosion we've had. I'm in 3 feet of water on the bridge. I'm going to stay by the radio as long as I can before I have to go overboard."
Investigators found no evidence of people, a boat or even debris, the U.S. Coast Guard said, but the hunt for the suspect continues.
"It's still an active investigation," Charles Rowe of the USCG's New York office told CNN Thursday. The burden of paying for unneeded search and rescue operations is passed on to taxpayers, and the costs can be massive. "This guy is spending your money when he's doing this," Rowe said.
The estimated price of the rescue operation in the New Jersey was $300,000, and the Maryland case is already nearing $70,000.
"It's dangerous to the boating public, anybody who gets on a boat, and it's dangerous to first responders," according to Rowe. The USCG's New York office told CNN they've received a steady stream of spurious calls this summer, but nothing out of the ordinary, and none they can trace back to the New Jersey incident.
Making a false distress call is a felony with the maximum penalty of six years in prison, a $5,000 civil fine and a $250,000 criminal fine.
Anyone with information is asked to call the Coast Guard's Investigative Services team.