LANSING, Mich. (Michigan News Source) — A St. Clair County mariner instructor has admitted to steering students around Coast Guard rules—cutting corners, faking tests, and certifying unqualified sailors in a scheme prosecutors say could have sunk Great Lakes safety.

Mel Stackpoole, 62, admitted in federal court on Aug. 11 to falsifying records tied to U.S. Coast Guard oversight. His sentencing is set for Dec. 18, when he could face as much as two decades in prison and a fine of up to $250,000.

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Stackpoole owned and taught at Great Lakes Charter Training, a Coast Guard–approved program. Prosecutors say he slashed course hours, fed students exam answers, altered failing scores, and told them to lie about their medical history, drug use, and sea service. He then certified them as qualified mariners and sent the falsified records to the Coast Guard, according to The Detroit News.

“Mel Stackpoole has endangered the safety of everyone who uses the waterways of our Great Lakes,” U.S. Attorney Jerome Gorgon Jr. said. Coast Guard officials called the case a breach of trust that jeopardized both careers and maritime security.