After nearly three decades of research, dives, and tussles, Libert believes he's about to solve the mystery.
He was to lead a diving expedition over the weekend to an underwater site in northern Lake Michigan, where archaeologists and technicians were to try to determine whether a timber jutting from the bottom and other items beneath layers of sediment were what remained of the legendary Griffin.
"I'm numb from the excitement," said Libert, 59, a burly ex-football playe.
The just-retired intelligence analyst with the U.S. Department of Defense has a passion for maritime mysteries and has journeyed from Okinawa to the Florida Keys for diving expeditions. A biography posted on his website says he's advised searches for the Titanic, five Navy torpedo bombers lost in the Bermuda Triangle during World War II, and John Paul Jones' warship Bon Homme Richard, among others.
But his biggest goal is finding the Griffin. "It's the holy grail for the Great Lakes; it's No. 1 on the list," said Libert, who has homes in the Washington area and in Charlevoix, Mich.
It carried no gold or other treasure. Its value is historic and cultural.
"Just to know where she went and where she is would be of great interest," said Matthew Daley, a Grand Valley State University history professor and maritime researcher.
The fabled explorer, whose full name was Rene Robert Cavelier de la Salle, secured a grant from King Louis XIV of France to explore the American continent, build forts, and seek the reputed passage to China and Japan. His team constructed the Griffin on the Niagara River a few miles from the falls, naming it for the mythological figure with the head and wings of an eagle and the body of a lion. Although small by modern standards - an estimated 50 feet long and 13 feet wide - it was an impressive sight on the inland seas, with its three masts, square sails, and two cannons.
The vessel traversed Lakes Erie and Huron, then headed west on Lake Michigan, eventually stopping at Washington Island near the entrance to Green Bay. La Salle continued south by canoe while the Griffin prepared to retrace its journey. Father Louis Hennepin, a Catholic missionary who accompanied La Salle, wrote that the ship fired a farewell cannon blast as it glided into open water.
Among theories about its demise: It succumbed to a fierce storm; American Indians attacked and burned the ship; mutinous crewmen scuttled it and stole the furs. Libert, who says he spent years scouring the area and studying the writings of La Salle and Hennepin, is convinced it traveled only a short distance before sinking in a gale.
His big break came in October 2001. While scuba diving near tiny Poverty Island in murky Michigan waters, he smacked into a timber sticking nearly 11 feet out of the lake bed. It looked like part of a ship, with a tapered end and fastening pegs. Carbon testing of small samples indicated it could date to the Griffin time period, but wasn't conclusive.
Libert says the water depth is less than 100 feet in the area but won't divulge the precise location, saying other divers could loot or damage the wreckage.
Some remain skeptical that Libert has discovered the Griffin or that it remains intact. Ronald Mason, a professor emeritus in anthropology at Lawrence University in Wisconsin, said previous claims came up empty.
"I just cannot see a wooden-framed sailing vessel keeping together for a prolonged period of time, given the increasing and decreasing pressures and movement of currents in fairly shallow water," he said. "I wish them good luck. I wouldn't want to bet money on their chances."