An 81-year-old man from Montana has been sentenced to six months in federal prison for illegally using genetic material from endangered sheep to breed hybrid animals for trophy hunting.

Arthur “Jack” Schubarth’s controversial operation involved the creation of cloned embryos using tissue and testicles from the giant Marco Polo sheep hunted in Kyrgyzstan. His plan was to use the huge hybrid sheep for trophy hunting in the U.S.

U.S. District Court Judge Brian Morris, who noted the complexity of sentencing Schubarth, balanced the defendant’s age and clean criminal record against the need to deter similar actions in the future.

“I will have to work the rest of my life to repair everything I’ve done,” Schubarth told the judge before sentencing.

Schubarth’s attorney, Jason Holden, argued for probation, pointing out his client’s lifelong commitment to animal care and his achievement in cloning the Marco Polo sheep, named Montana Mountain King. Mr. Holden emphasized the severe impact the incident had on Schubarth’s life, reputation, and family. “I think this has broken him,” Mr. Holden said, according to the Associated Press.

“Schubarth’s criminal conduct is not how Montanans treat our wildlife population,” U.S. Attorney Jesse Laslovich said. “Indeed, his actions threatened Montana’s native wildlife species for no other reason than he and his co-conspirators wanted to make more money.”