Six Mexican men have pleaded guilty to federal charges of conspiring to sell large amounts of the drug crystal methamphetamine in the D.C. area, federal prosecutors announced Thursday.

All six were indicted in December 2010 on drug charges after their arrests in Georgia and North Carolina. Prosecutors said authorities seized 50 pounds of methamphetamine, six pounds of marijuana and three guns in coordinated searches on Dec. 10 and Dec. 11 in those two states. D.C. police estimate the street value of the seized drugs was more than $3.5 million.

The ring had ties to the “La Familia” drug cartel in Mexico and was working “to create a distribution network and market for crystal methamphetamine in the Washington, D.C., area” at the time of the arrests, prosecutors said in a press release.

According to court papers, undercover D.C. police bought narcotics in the District from dealers last year and those purchases eventually led authorities to the drug ring in Georgia and North Carolina.

“We thwarted a very dangerous organization from establishing a crystal meth distribution network in” the D.C. area, U.S. Attorney Ronald C. Machen said in an interview.

On Thursday, Alfonso Martinez-Cruz, 40, pleaded guilty to a charge of conspiring to distribute and possession with intent to distribute methamphetamine. Under federal guidelines, he faces a prison term of about 5 to 7 years when sentenced Jan. 18 by Senior U.S. District Judge Thomas F. Hogan.

Five others have previously pleaded guilty in the case, prosecutors said. The alleged ring-leader, Alberto Garcia Calderon, 36, is scheduled to be sentenced Dec. 5. Under the sentencing guidelines, he faces between 15 and 18 years in prison, prosecutors said.