Arthur “Jack” Schubarth, 80, from the US state of Montana, last week pleaded guilty to two wildlife offences committed as part of what prosecutors describe as “a decade-long effort to create giant sheep hybrids in the United States”.

The plot involved bringing parts of the largest sheep in the world, Marco Polo argali sheep (Ovis ammon polii), from Kyrgyzstan into the United States, and then using their genetic material to create cloned embryos.

Mr Schubarth then implanted the embryos in ewes on his ranch, resulting in a single, pure genetic male Marco Polo argali that he named “Montana Mountain King” or MMK.

He then worked with others to use MMK’s semen to artificially impregnate various other species of ewes — all of which were prohibited in Montana — and create hybrid animals. Their goal was to create a larger and more valuable species of sheep to sell to captive hunting facilities, primarily in Texas.

Assistant Attorney General Todd Kim of the US Justice Department’s environment and natural resources division said: “This was an audacious scheme to create massive hybrid sheep species to be sold and hunted as trophies.

“In pursuit of this scheme, Schubarth violated international law and the Lacey Act, both of which protect the viability and health of native populations of animals.”

For each offence, Mr Schubarth faces a maximum penalty of five years in prison, a fine of up to $250,000 and three years of supervised release. He is scheduled to be sentenced on Thursday 11 July.