SIOUX FALLS | A federal judge recused himself from Beef Products Inc.'s defamation lawsuit against ABC News because his daughter-in-law is a part-time ABC employee, according a court document filed Monday.

Judge Lawrence L. Piersol disclosed the relationship in a Nov. 1 letter to the attorneys in the case. A copy of the letter was posted Monday in U.S. District Court in Sioux Falls.

On Nov. 19, Piersol recused himself from the case but did not offer an explanation. The case was reassigned to Chief Judge Karen Schreier.

ABC is accused of defaming BPI's signature lean finely textured beef in a series of news stories in March. The Dakota Dunes-based company, which is seeking $1.2 billion in damages, claims the national news network misled consumers into believing the product is unhealthy and unsafe.

Piersol's daughter-in-law, who was not identified in the letter, works as a producer on the "Good Morning America" show three days a week. After the defamation suit was moved from Union County Circuit Court to federal court, Piersol asked his daughter-in-law "if she did any work on any of the stories or anything else involved in this litigation, and she had not," according to the letter, signed by U.S. District Court Clerk Joseph Haas.