The layoffs continued for months and months. Gregory saw people fired and workers running out of the Dade offices in tears. "These people were scared to death," he said. "This was their livelihood. Some people couldn't bear it. It was a horrible place to work." Some would get an hour's notice before being shown the door.

The plant added higher fencing and concertina wire, Gregory said. Each day, a pair of security guards would check his back seat and trunk on the way out to make sure he wasn't stealing any office supplies. "It was all so well orchestrated," he said. "And so evil."

The Romney campaign, Bain Capital, and Siemens, which bought Dade Behring's operations in 2007, did not respond to requests for comment.