The State newspaper reported the documents surfaced Tuesday during the sentencing of a cockfighting operator.
The documents say 14 fighting derbies were held each year in Swansea, about 20 miles south of Columbia. Prosecutors said in court filings that more than 20,300 birds were killed during the 18 years of the cockfighting operation.
U.S. District Judge Cameron Currie sentenced 52-year-old Jimmy Collins of Duncan to 21 months in prison. He also was fined $5,000. The newspaper said prosecutors had hoped the numbers would convince Currie to impose a longer sentence.
Collins is appealing his conviction.