Sharpshooters killed a farm herd of some 560 elk near Rochester this month, and tests of the animals found three infected with chronic wasting disease, state officials said Friday. The slaughter was ordered after one of the animals tested positive for the disease in January.

The animals lived on the 1,300-acre Elk Farm LLC near Pine Island, the largest elk farm in the state. The farm, bought by Tower Investments of Woodland, Calif., in 2006, is part of a 2,300-acre tract set to become a bioscience research and manufacturing center called Elk Run, with offices, shops, homes and 15 to 25 companies.

The carcasses were sent to a landfill, except for the three that tested positive, which were destroyed at a special facility at the University of Minnesota. The U.S. Department of Agriculture (USDA) paid Tower Investments a fair market value for the elk, said Paul Anderson, assistant director of the Minnesota Board of Animal Health.

The USDA sharpshooters began shooting the animals last month. Tests were conducted at a USDA lab in Ames, Iowa.

Chronic wasting disease kills elk and deer after infecting their brains and nervous system. The animals spread it through nose-to-nose contact. It does not spread to people. It was first detected in farmed elk in 2002, prompting fears that it could spread to the state's population of some 1 million wild deer.

Matt McKinney • 612-673-7329