FULTON, Mo. (AP) — The last of 13 defendants has pleaded guilty in a conspiracy to distribute millions of dollars in synthetic drugs known as K2 at Callaway County businesses.

Forty-three-year-old Raja Amer, of Roseville, California, pleaded guilty Tuesday to conspiracy to commit mail fraud.

Federal prosecutors say Nawaz and other conspirators in California sold K2 to several Callaway County businesses, generating $6.6 million in gross proceeds.

As part of his plea, Nawaz agreed to forfeit $2.9 million.

The businesses bought K2 from people Nawaz and others from December 2012 to July 2015 and sold them to others. At least 251 shipments of K2 mislabeled as such things as incense or aroma therapy were made to Callaway County.

Sentencing has not been scheduled.