LAREDO, Texas — A South Carolina man has been sentenced in South Texas to 15 years in prison for his role in a drug-trafficking conspiracy and for possessing a firearm during a drug deal.

U.S. District Judge George Kazen sentenced 29-year-old Calvin Epps of Hopkins, S.C., on Friday in Laredo. Epps was arrested in Columbia, S.C., in March 2012, two months after a tractor-trailer loaded with 500 pounds of marijuana bound for South Carolina was seized by authorities in Texas.

A co-defendant received the same sentence last week.

The conspiracy unraveled when one of the suspects negotiated with people he thought were members of the Zetas drug cartel but were actually undercover agents. The suspects had agreed to provide military-style weapons and training, and to kill someone in return for money and drugs.